Topic 2 · Changing state — the scripts

What you are deciding: go-ahead for video generation on this topic, card by card.

Out of scope: articles and PP100 items (not on this page).

Here: the intro video, 8 lesson videos (3 marked by the author as “could do without a video”) and the summary video, in teaching order. Each card: the script, the attached question, then the quiz the student meets after the video.

How: tap one button per card. Taps and notes save as you go and are sent; the Notes tab shows what has gone and re-sends.

Intro video · teaches nothing, opens the question119 words · about 1:00

Introduction: Changing state

Script

Say	Screen
Here is a student in a kitchen on a hot afternoon.	[a kitchen; a student at the counter]
She leaves an ice cube on a plate, and when she comes back it is a puddle of water.	[the cube shrinks into a puddle]
An hour later, the plate is dry.	[clock advances; the puddle shrinks to nothing]
She takes a cold can from the fridge, and within a minute drops of water cover it.	[the fridge opens; the can; drops form on it]
Nobody touched the ice, the puddle or the can.	[chip: NOBODY TOUCHED THEM]
So where did the ice and the puddle go, and where did the drops on the can come from?	[question marks over the plate and the can]
To find out, we will look at what the particles do when water changes from one state to another, and back again.	[the plate and the can stay]
Okay, so are you ready to find out where the ice and the puddle went?	[the three replies appear]

The ready line's poll — the attached item (no key; the intro teaches nothing)

video

Okay, so are you ready to find out where the ice and the puddle went?

A Yes, let's go! — Great. Here we go.
B Not sure yet — That's fine. We take it one change at a time.
C Let me watch that again — Good idea. Watch it again, then come back.

Answer

No key. A poll: every reply is accepted with its friendly line.

Your note · the intro video

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Lesson 1 of 8Author: definitely a video195 words · about 1:38

Ice melts

MAT-020 · Melting — Predict what happens to a solid when thermal energy is added, at the particle level.

Script

Say	Screen
Here is an ice cube on a plate in a warm kitchen.	[ice cube on a plate; chip: WARM KITCHEN]
Thirty minutes later, the plate holds a small puddle of water.	[clock runs 30 min; the cube shrinks into a puddle]
Nobody touched the ice, so what happened to its particles?	[chip: NOBODY TOUCHED IT; question mark over the puddle]
The warm kitchen changed how its particles move.	[magnifier hovers over the puddle]
Ice is a solid: its particles are packed tightly, touching, in fixed positions.	[magnifier grows into the solid box; chips: TOUCHING, FIXED POSITIONS]
Each particle vibrates on the spot.	[all particles jiggle in place]
The warm air heats the cold ice.	[arrow up under the box, labelled HEAT IN]
Heating gives the particles energy.	[chip: HEATING GIVES ENERGY]
The particles vibrate faster and faster.	[jiggles grow larger]
The particles break out of their fixed positions.	[middle panel: the grid loosens; particles drift]
Now the particles touch with no fixed positions and slide past one another.	[liquid box: particles slide; chip: SLIDE PAST]
The solid has become a liquid.	[label SOLID becomes LIQUID; puddle beside the liquid box]
A solid turning into a liquid is called melting.	[chip: MELTING]
Now consider a frozen fruit pop in a warm lunchbox.	[fruit pop in a lunchbox]
The warm lunchbox heats the pop and gives its particles energy.	[HEAT IN arrow; chip: HEATING GIVES ENERGY]
The particles break loose, and the pop melts.	[grid loosens; the pop slumps into liquid]
So, heating gives particles energy.	[the rule slide: the three melting panels, solid box, loosening grid, liquid box; chip HEATING GIVES ENERGY; nothing else printed]
The particles in a solid vibrate harder, break out of their fixed positions and slide past one another.	[the middle panel: the grid loosens and the particles slide]
The solid melts into a liquid.	[the puddle beside the liquid box; chip MELTING]
So on the plate, the warm kitchen gave the ice particles energy, they broke loose, and the ice melted.	[ice cube on the plate; HEAT IN arrow; the puddle]
Okay, now your turn.	[the rule slide's images hold; closing screen: bullets — • Heating gives particles energy. • The particles in a solid vibrate harder, break out of their fixed positions and slide past one another. • A solid turning into a liquid is called melting.]

“Okay, now your turn.” — the attached question

video

An ice cube melts on a plate in a warm kitchen. What does heating make its particles do?

A break out of their fixed positions and slide
B stop moving

Answer

Key: A — break out of their fixed positions and slide

Heating gives the particles energy.
They break out of their fixed positions and slide.
The ice melts.

Feedback per option

A Heating gives particles energy, so they vibrate harder and break loose.
B Heating speeds particles up; it never stops them.

Quiz after the video — the mastery check, 12 items

Q1recall

A bowl of oatmeal is heated from 10 °C to 60 °C. What happens to the speed of its particles?

A The particles move faster.
B The particles move more slowly.
C The speed of the particles does not change.

Answer

Key: A — The particles move faster.

Heating a substance makes its particles move faster.
The oatmeal is heated, so its particles move faster.

Feedback per option

A Heating makes particles move faster.
B Cooling slows particles down; heating speeds them up.
C Heating changes the speed of the particles: they move faster.

Q2recall

How are the particles in a solid arranged?

A far apart, with empty space between them
B touching, in fixed positions
C touching, with no fixed positions

Answer

Key: B — touching, in fixed positions

In a solid the particles are packed tightly, touching, in fixed positions.
Each particle vibrates on the spot.

Feedback per option

A Particles far apart with empty space between them are a gas. In a solid the particles touch.
B In a solid the particles are packed tightly, touching, in fixed positions.
C Particles touching with no fixed positions are a liquid. In a solid the particles have fixed positions.

Q3term

What is a solid turning into a liquid called?

Typed answer

Answer

Accepted: melting · melt

A solid turning into a liquid is called melting.

Q4term

What is melting?

A a liquid turning into a solid
B a solid getting warmer but staying solid
C a solid turning into a liquid

Answer

Key: C — a solid turning into a liquid

A solid turning into a liquid is called melting.

Feedback per option

A A liquid turning into a solid is the reverse change. Melting is a solid turning into a liquid.
B A warm solid is still a solid. Melting is a solid turning into a liquid.
C A solid turning into a liquid is called melting.

Q5what

A bar of chocolate is left in the sun on a hot day. What happens to the chocolate?

A The chocolate turns into a liquid.
B The chocolate turns into a gas.
C The chocolate stays a solid.

Answer

Key: A — The chocolate turns into a liquid.

The sun heats the chocolate.
Heating gives the particles energy.
The particles break out of their fixed positions and slide.
So the chocolate melts into a liquid.

Feedback per option

A The sun heats the chocolate, and the solid melts into a liquid.
B The sun melts the solid chocolate into a liquid. The chocolate does not turn into a gas.
C Heating gives the particles energy, and the solid melts.

Q6why

Snow lies on a sidewalk in the morning. By the afternoon, the sun has turned the snow into water. Explain why the snow melted, using particles.

Starter: The snow melted because…

Answer

Model answer · ['heat flowed into the snow and gave its particles energy', 'the particles vibrated faster and broke out of their fixed positions', 'the particles now slide past one another, which is a liquid'] points

The snow melted because heat flowed from the warm air and sunshine into the snow.
Heating gives the particles energy.
The snow particles vibrated faster and faster.
The particles broke out of their fixed positions.
Now the particles slide past one another, so the snow is liquid water.

Q7misconception

An icicle drips in the sun. Diego says: "Each ice particle is turning into a water particle." Is Diego correct?

A yes
B no

Answer

Key: B — no

Ice and water are made of the same particles.
Heating gave the particles energy.
The particles broke out of their fixed positions and now slide past one another.
Only their arrangement and movement changed.

Feedback per option

A Ice and water look different, but they are the same particles. The particles broke out of their fixed positions and now slide.
B The particles do not change. The same particles broke out of their fixed positions and now slide past one another.

Q8transfer

Solid bacon fat sits in a cold pan. The burner is lit, and the fat turns clear and runny. What happens to the fat's particles?

A The particles stop moving.
B The particles break out of their fixed positions and slide past one another.
C The particles stay in fixed positions and vibrate more slowly.

Answer

Key: B — The particles break out of their fixed positions and slide past one another.

The burner heats the pan, and the pan heats the fat.
Heating gives the particles energy.
The particles vibrate harder and break out of their fixed positions.
Now the particles slide past one another, so the fat is a liquid.

Feedback per option

A Particles never stop moving. Heating gives them energy.
B The hot pan gives the particles energy, so they break loose and slide.
C Heating makes the particles vibrate harder, not more slowly.

Q9fluency

A block of cheese sits near a hot stove and turns into a liquid. Is this melting?

A yes
B no

Answer

Key: A — yes

The cheese was a solid and became a liquid.
A solid turning into a liquid is called melting.

Feedback per option

A A solid turned into a liquid.
B A solid turned into a liquid, and that is melting.

Q10fluency

Water in a pond turns into solid ice overnight. Is this melting?

A yes
B no

Answer

Key: B — no

The pond water was a liquid and became a solid.
Melting is the reverse: a solid turning into a liquid.

Feedback per option

A Melting is a solid turning into a liquid. The pond water went the other way.
B A liquid turned into a solid. Melting is a solid turning into a liquid.

Q11fluency

Wet paint on a fence dries. Is this melting?

A yes
B no

Answer

Key: B — no

The paint was a liquid, and no solid turned into a liquid.
Melting is a solid turning into a liquid.

Feedback per option

A No solid turned into a liquid here.
B No solid turned into a liquid here. Melting is a solid turning into a liquid.

Q12fluency

Solid coconut oil in a jar turns into a liquid on a hot day. Is this melting?

A yes
B no

Answer

Key: A — yes

The coconut oil was a solid and became a liquid.
A solid turning into a liquid is called melting.

Feedback per option

A A solid turned into a liquid.
B A solid turned into a liquid, and that is melting.

Your note · lesson 1: Ice melts

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Lesson 2 of 8Author: definitely a video199 words · about 1:40

Water freezes

MAT-021 · Freezing — Predict what happens to a liquid when thermal energy is removed, at the particle level.

Script

Say	Screen
Here is a tray of water in a freezer at minus 18 degrees Celsius.	[tray of water slides into a freezer; label −18 °C]
Three hours later, every cube is solid.	[clock runs 3 h; the cubes turn to ice]
Nobody touched the water, so what happened to its particles?	[chip: NOBODY TOUCHED IT; question mark over the tray]
The cold freezer changed how its particles move.	[magnifier hovers over the tray]
Water is a liquid: its particles touch with no fixed positions and slide past one another.	[magnifier grows into the liquid box; particles slide; chip: NO FIXED POSITIONS]
The warm water heats the cold freezer air, so the water cools.	[arrow down under the box, labelled HEAT OUT]
Cooling takes energy away from the particles, so they slow down.	[chip: COOLING TAKES ENERGY AWAY; sliding slows]
The slow particles stop sliding and lock into fixed positions.	[middle panel: particles snap into the grid; chip: FIXED POSITIONS]
Each particle still vibrates on the spot.	[small jiggles; chip: VIBRATES ON THE SPOT]
The liquid has become a solid.	[label LIQUID becomes SOLID; ice cube beside the box]
A liquid turning into a solid is called freezing.	[chip: FREEZING]
Freezing is melting run backwards.	[the melting arrow reverses]
Now consider melted chocolate in a mold in a fridge.	[liquid chocolate in a mold]
The chocolate cools in the fridge, and cooling takes energy from its particles.	[HEAT OUT arrow; chip: COOLING TAKES ENERGY AWAY]
The particles lock into fixed positions, and the chocolate freezes.	[particles snap into a grid; the bar pops out]
So, cooling takes energy away from particles.	[the rule slide: the three freezing panels, liquid box, snapping grid, solid box; chip COOLING TAKES ENERGY AWAY; nothing else printed]
The particles in a liquid slow down, stop sliding and lock into fixed positions.	[the middle panel: particles snap into the grid]
The liquid freezes into a solid.	[the ice cube beside the solid box; chip FREEZING]
So in the tray, the freezer took energy from the water particles, they locked into place, and the water froze.	[tray in the freezer; HEAT OUT arrow; the tray of ice cubes]
Okay, now your turn.	[the rule slide's images hold; closing screen: bullets — • Cooling takes energy away from particles. • The particles in a liquid slow down, stop sliding and lock into fixed positions. • A liquid turning into a solid is called freezing.]

“Okay, now your turn.” — the attached question

video

A tray of water freezes in a freezer. What does cooling make its particles do?

A fly apart
B lock into fixed positions

Answer

Key: B — lock into fixed positions

Cooling takes energy away.
The particles slow, stop sliding, and lock into fixed positions.
The water freezes.

Feedback per option

A Cooling slows particles; flying apart is what a gas does.
B Slower particles stop sliding and lock into place.

Quiz after the video — the mastery check, 12 items

Q1recall

What is melting?

A a solid turning into a liquid
B a liquid turning into a solid
C a solid getting warmer but staying solid

Answer

Key: A — a solid turning into a liquid

A solid turning into a liquid is called melting.

Feedback per option

A A solid turning into a liquid is called melting.
B A liquid turning into a solid is the reverse change. Melting is a solid turning into a liquid.
C A warm solid is still a solid. Melting is a solid turning into a liquid.

Q2recall

A cup of tea cools from 60 °C to 20 °C. What happens to the speed of its particles?

A The particles move faster.
B The particles stop moving.
C The particles move more slowly.

Answer

Key: C — The particles move more slowly.

Cooling a substance makes its particles move more slowly.
The tea is cooled, so its particles move more slowly.

Feedback per option

A Cooling slows particles down; heating speeds them up.
B Particles never stop moving. Cooling only slows them down.
C Cooling makes particles move more slowly.

Q3term

What is a liquid turning into a solid called?

Typed answer

Answer

Accepted: freezing · freeze

A liquid turning into a solid is called freezing.

Q4term

What is freezing?

A a liquid getting colder but staying liquid
B a liquid turning into a solid
C a solid turning into a liquid

Answer

Key: B — a liquid turning into a solid

A liquid turning into a solid is called freezing.

Feedback per option

A A cold liquid is still a liquid. Freezing is a liquid turning into a solid.
B A liquid turning into a solid is called freezing.
C A solid turning into a liquid is melting. Freezing is a liquid turning into a solid.

Q5what

Hot, runny caramel is poured onto a tray and left to cool. What happens to the caramel?

A The caramel turns into a gas.
B The caramel stays a runny liquid.
C The caramel turns into a solid.

Answer

Key: C — The caramel turns into a solid.

Heat flows out of the hot caramel into the cooler air.
Cooling takes energy away from the particles.
The particles slow down and lock into fixed positions.
So the caramel freezes into a solid.

Feedback per option

A Cooling takes energy away; the liquid turns into a solid, not a gas.
B Cooling slows the particles until they lock into fixed positions.
C Cooling takes energy away from the particles, and the liquid freezes into a solid.

Q6why

A bucket of water is left outside on a very cold night. By morning the water has turned into ice. Explain why the water froze, using particles.

Starter: The water froze because…

Answer

Model answer · ['heat flowed out of the water, so cooling took energy away from its particles', 'the particles slowed down and stopped sliding', 'the particles locked into fixed positions, which is a solid'] points

The water froze because heat flowed out of the water into the cold night air.
Cooling takes energy away from the particles.
The water particles moved more and more slowly.
The particles stopped sliding past one another.
Each particle locked into a fixed position, so the water is now solid ice.

Q7misconception

A puddle turns into ice on a cold night. Aisha says: "The water particles have stopped moving completely." Is Aisha correct?

A yes
B no

Answer

Key: B — no

Particles are always moving.
Cooling slowed the water particles down.
The particles locked into fixed positions.
In the ice each particle still vibrates on the spot.

Feedback per option

A Ice looks frozen still, but particles never stop moving. In the ice each particle vibrates on the spot.
B Particles never stop moving. In the ice each particle vibrates on the spot.

Q8transfer

Melted metal is poured into a mold and left to cool. What happens to the metal's particles as it cools?

A The particles slow down and lock into fixed positions.
B The particles speed up and fly apart.
C The particles keep sliding past one another.

Answer

Key: A — The particles slow down and lock into fixed positions.

Heat flows out of the hot metal into the cooler air and mold.
Cooling takes energy away from the particles.
The particles slow down and stop sliding.
Each particle locks into a fixed position, so the metal is now a solid.

Feedback per option

A Cooling takes energy away, so the particles slow down and lock into place.
B Cooling slows particles down; it does not speed them up.
C The slow particles stop sliding and lock into fixed positions.

Q9fluency

Hailstones on a deck turn into water within an hour. Is this melting or freezing?

A melting
B freezing

Answer

Key: A — melting

The hailstones were solid and became liquid water.
A solid turning into a liquid is called melting.

Feedback per option

A A solid turned into a liquid.
B A solid turned into a liquid. That is melting.

Q10fluency

Olive oil turns solid in a cold garage. Is this melting or freezing?

A melting
B freezing

Answer

Key: B — freezing

The olive oil was a liquid and became a solid.
A liquid turning into a solid is called freezing.

Feedback per option

A A liquid turned into a solid. That is freezing.
B A liquid turned into a solid.

Q11fluency

Hot lava flows down a hillside, cools and turns into solid rock. Is this melting or freezing?

A melting
B freezing

Answer

Key: B — freezing

The lava was a liquid and became a solid.
A liquid turning into a solid is called freezing.

Feedback per option

A A liquid turned into a solid. That is freezing.
B A liquid turned into a solid.

Q12fluency

A frozen lake turns back into liquid water in spring. Is this melting or freezing?

A melting
B freezing

Answer

Key: A — melting

The lake ice was a solid and became a liquid.
A solid turning into a liquid is called melting.

Feedback per option

A A solid turned into a liquid.
B A solid turned into a liquid. That is melting.

Your note · lesson 2: Water freezes

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Lesson 3 of 8Author: definitely a video198 words · about 1:39

Water turns to a gas: evaporation and boiling

MAT-022 · Evaporation and boiling — Predict what happens to a liquid when enough thermal energy is added.

Script

Say	Screen
Here is a puddle on a playground after rain.	[puddle on a playground]
The sun comes out, and by afternoon the puddle has gone.	[sun appears; clock runs; puddle shrinks to nothing]
Nobody mopped it up, so where did the water go?	[question mark over the dry ground]
It went into the air, as a gas.	[faint particles rise from the dry ground into the air]
The sun heats the puddle, giving its particles energy.	[magnifier on the surface: liquid box; HEAT IN arrow; chip: HEATING GIVES ENERGY]
The fastest surface particles fly off.	[one particle shoots up from the surface, then another]
In the air they are far apart and flying, so they are a gas.	[particles above the surface scatter; label GAS]
Water as a gas is called water vapor.	[chip: WATER VAPOR]
A liquid turning into a gas from its surface is called evaporation.	[chip: EVAPORATION; the puddle shrinks as particles leave]
Now consider a pan of water at 100 degrees Celsius.	[pan on a burner; thermometer reads 100 °C]
Particles all through the water fly apart into pockets of gas.	[magnifier deep in the water; a bubble forms, drawn as the gas box]
Each bubble is water vapor; it rises and bursts.	[bubbles rise and burst at the top]
A liquid turning into a gas all through the liquid, as bubbles, is called boiling.	[chip: BOILING]
The bubbles in boiling water are water vapor, not air.	[chip: WATER VAPOR, NOT AIR]
So, heating gives particles energy.	[the rule slide: the puddle and the pan; chip HEATING GIVES ENERGY; nothing else printed]
The fastest particles at the surface fly off as a gas: that is evaporation.	[the puddle; particles leave its surface; chip EVAPORATION]
At 100 degrees Celsius, water particles fly off all through the liquid as bubbles: that is boiling.	[the pan; bubbles rise; chip BOILING]
So on the playground, the sun gave the puddle's particles energy, and the fastest flew off.	[the dry playground; vapor particles in the air]
Okay, now your turn.	[the rule slide's images hold; closing screen: bullets — • Heating gives particles energy. • The fastest particles at the surface fly off as a gas: that is evaporation. • At 100 °C, water particles fly off all through the liquid as bubbles: that is boiling.]

“Okay, now your turn.” — the attached question

video

A pan of water boils on a stove. What are the bubbles made of?

A air
B water vapor

Answer

Key: B — water vapor

In boiling water, particles fly off all through the liquid as bubbles of water vapor.

Feedback per option

A The bubbles are water that has turned into a gas.
B Boiling makes bubbles of water vapor all through the water.

Quiz after the video — the mastery check, 12 items

Q1recall

How are the particles in a gas arranged?

A touching, in fixed positions
B touching, with no fixed positions
C far apart, with empty space between them

Answer

Key: C — far apart, with empty space between them

In a gas the particles are far apart, with empty space between them.
The gas particles fly fast in every direction.

Feedback per option

A Particles touching in fixed positions are a solid. In a gas the particles are far apart.
B Particles touching with no fixed positions are a liquid. In a gas the particles are far apart.
C In a gas the particles are far apart, with empty space between them.

Q2term

What is water as a gas called?

Typed answer

Answer

Accepted: water vapor · vapor · water vapour

Water as a gas is called water vapor.

Q3term

What is a liquid turning into a gas from its surface called?

Typed answer

Answer

Accepted: evaporation · evaporating · evaporate

A liquid turning into a gas from its surface is called evaporation.

Q4term

What is boiling?

A a liquid turning into a gas from its surface only
B a liquid turning into a gas all through the liquid, as bubbles
C a gas turning back into a liquid

Answer

Key: B — a liquid turning into a gas all through the liquid, as bubbles

A liquid turning into a gas all through the liquid, as bubbles, is called boiling.

Feedback per option

A A liquid turning into a gas from its surface only is evaporation. Boiling happens all through the liquid.
B Bubbles of gas form all through the liquid. That is boiling.
C A gas turning into a liquid is the reverse change. Boiling is a liquid turning into a gas, as bubbles.

Q5what

Wet laundry hangs on a line on a breezy day. By evening the laundry is dry. What happened to the water?

A The water went into the air as a gas.
B The water soaked deeper into the cloth.
C The water went into the air as tiny drops of liquid.

Answer

Key: A — The water went into the air as a gas.

Some particles at the surface of the wet cloth move fast enough to fly off into the air as water vapor.
Particle after particle left, so the laundry dried.

Feedback per option

A The fastest particles flew off the surface into the air as water vapor.
B The cloth is dry, so the water is not in it. The water left as a gas.
C Tiny drops are liquid water. The water left the cloth as single particles, far apart: a gas.

Q6why

A shallow dish of water is left on a sunny windowsill. Three days later the dish is empty. Explain where the water went, using particles.

Starter: The water went…

Answer

Model answer · ['the water is in the air as water vapor (a gas)', 'heating gave the particles energy', 'the fastest particles at the surface flew off, one after another, until none were left'] points

The water went into the air as water vapor.
The sun heated the water and gave its particles energy.
The fastest particles at the surface flew off into the air.
In the air these particles are far apart and fly in every direction, so they are a gas.
Particle after particle left until the dish was empty.

Q7misconception

Water in a glass teapot on a stove reaches 100 °C, and bubbles rise through it. Ravi says: "The bubbles are made of air." Is Ravi correct?

A yes
B no

Answer

Key: B — no

At 100 °C the water particles all through the teapot have enough energy to fly apart.
The particles fly apart into pockets of gas.
Each pocket is a bubble of water vapor, not air.

Feedback per option

A The bubbles look like air, but they form all through the water, far from any air. They are pockets of water vapor.
B The bubbles are water vapor. Water particles all through the teapot fly apart into pockets of gas.

Q8transfer

Rain leaves drops on the hood of a car. An hour of sunshine later, the hood is dry. What happened to the water?

A The water turned into a solid.
B The water soaked into the metal.
C The fastest water particles flew off the surface into the air as a gas.

Answer

Key: C — The fastest water particles flew off the surface into the air as a gas.

The fastest water particles at the surface flew off into the air as a gas.
Particle after particle left, so the hood dried.
The water evaporated.

Feedback per option

A Nothing cooled the water. Its particles flew off into the air as a gas.
B Water cannot soak into metal. The hood is dry because the water left as a gas.
C The fastest particles at the surface flew off into the air. That is evaporation.

Q9fluency

Water in a pot over a campfire reaches 100 °C, and bubbles form all through it. Is this evaporation or boiling?

A evaporation
B boiling

Answer

Key: B — boiling

Bubbles of gas form all through the water.
A liquid turning into a gas all through the liquid, as bubbles, is called boiling.

Feedback per option

A Evaporation happens from the surface only. Here bubbles form all through the water.
B Bubbles of gas form all through the liquid. That is boiling.

Q10fluency

A wet towel dries slowly on a hook. Is this evaporation or boiling?

A evaporation
B boiling

Answer

Key: A — evaporation

The water left the towel from its surface, a particle at a time.
A liquid turning into a gas from its surface is called evaporation.

Feedback per option

A The water left the surface of the towel a particle at a time. That is evaporation.
B No bubbles formed; the towel is not at 100 °C. The water left from the surface.

Q11fluency

Sweat disappears from a runner's skin. Is this evaporation or boiling?

A evaporation
B boiling

Answer

Key: A — evaporation

The sweat left from its surface, a particle at a time.
A liquid turning into a gas from its surface is called evaporation.

Feedback per option

A The sweat left the skin's surface a particle at a time. That is evaporation.
B No bubbles formed; skin is far below 100 °C. The sweat left from the surface.

Q12fluency

A pot of chili on a stove reaches 100 °C, and bubbles rise all through it. Is this evaporation or boiling?

A evaporation
B boiling

Answer

Key: B — boiling

Bubbles form all through the chili.
A liquid turning into a gas all through the liquid, as bubbles, is called boiling.

Feedback per option

A Evaporation happens from the surface only. Here bubbles form all through the chili.
B Bubbles form all through the liquid. That is boiling.

Your note · lesson 3: Water turns to a gas: evaporation and boiling

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Lesson 4 of 8Author: definitely a video198 words · about 1:39

Water vapor turns back to liquid

MAT-023 · Condensation — Predict what happens to a gas when thermal energy is removed.

Script

Say	Screen
Here is a can of soda from the fridge on a warm, humid day.	[cold can; chips: WARM, HUMID]
Within a minute, drops of water cover the can.	[clock runs 1 min; drops appear on the can]
The can was dry, so where did the water come from?	[question mark beside the can]
It came from the air.	[the air around the can highlighted]
The air holds water vapor: water particles flying about as a gas.	[magnifier: gas box beside the can wall; label WATER VAPOR]
A warmer thing always heats a colder thing.	[chip: WARM HEATS COLD]
So the warm air heats the cold can, and the air touching the can cools.	[HEAT OUT arrow from the air into the can]
Cooling takes energy away from the particles.	[chip: COOLING TAKES ENERGY AWAY]
Water vapor particles hit the cold can and slow down.	[a particle hits the can wall; its arrow shortens]
The slow particles crowd together on the can.	[particles gather on the wall into a heap]
Now the particles touch and slide past one another.	[liquid box on the can wall; chip: SLIDE PAST]
The gas has become a liquid.	[label GAS becomes LIQUID; drops on the can]
A gas turning into a liquid is called condensation.	[chip: CONDENSATION]
Condensation is evaporation run backwards.	[the evaporation arrow reverses]
Now consider a cold car window.	[car interior; cold glass]
Water vapor from people's breath hits the glass, slows down and crowds together.	[particles gather on the glass]
The window mists over.	[mist spreads across the glass]
So, cooling takes energy away from particles.	[the rule slide: the can and the gas box; chip COOLING TAKES ENERGY AWAY; nothing else printed]
Gas particles that touch a cold surface slow down and crowd together, touching and sliding.	[particles gather on the can wall into the liquid box]
The gas condenses into a liquid.	[drops on the can; chip CONDENSATION]
So the cold can took energy from the vapor particles, and they crowded into drops.	[the can; HEAT OUT arrow; drops on the can]
Okay, now your turn.	[the rule slide's images hold; closing screen: bullets — • Cooling takes energy away from particles. • Gas particles that touch a cold surface slow down and crowd together, touching and sliding. • A gas turning into a liquid is called condensation.]

“Okay, now your turn.” — the attached question

video

Drops of water form on a cold can on a humid day. Where does the water come from?

A water vapor in the air
B inside the can

Answer

Key: A — water vapor in the air

Water vapor particles in the air hit the cold can.
They slow down and crowd together into liquid drops.

Feedback per option

A Water vapor particles hit the cold can, slow down, and crowd into drops.
B The can is sealed. The water comes from the air.

Quiz after the video — the mastery check, 12 items

Q1recall

What is water vapor?

A water as a solid
B water as a liquid
C water as a gas

Answer

Key: C — water as a gas

Water as a gas is called water vapor.

Feedback per option

A Water as a solid is ice.
B Water as a liquid is just water.
C Water as a gas is called water vapor.

Q2recall

A mug of cocoa cools from 80 °C to 40 °C. What happens to the speed of its particles?

A The particles move more slowly.
B The particles move faster.
C The speed of the particles does not change.

Answer

Key: A — The particles move more slowly.

Cooling a substance makes its particles move more slowly.
The cocoa is cooled, so its particles move more slowly.

Feedback per option

A Cooling makes particles move more slowly.
B Heating speeds particles up; cooling slows them down.
C Cooling changes the speed of the particles: they move more slowly.

Q3term

What is a gas turning into a liquid called?

Typed answer

Answer

Accepted: condensation · condensing · condense

A gas turning into a liquid is called condensation.

Q4term

What is condensation?

A a liquid turning into a gas
B a gas turning into a liquid
C a gas getting colder but staying a gas

Answer

Key: B — a gas turning into a liquid

A gas turning into a liquid is called condensation.

Feedback per option

A A liquid turning into a gas is evaporation. Condensation is a gas turning into a liquid.
B A gas turning into a liquid is called condensation.
C A cold gas is still a gas. Condensation is a gas turning into a liquid.

Q5what

During a hot shower, the bathroom mirror fogs up. What forms on the mirror?

A tiny drops of liquid water
B a thin layer of ice
C a layer of soap

Answer

Key: A — tiny drops of liquid water

The hot shower filled the air with water vapor.
The mirror is cooler than the air, so heat flows from the air into the mirror.
Water vapor particles that hit the mirror slow down and crowd together.
The water vapor condenses into tiny drops of liquid water.

Feedback per option

A Water vapor from the shower hit the cooler mirror and condensed into tiny drops.
B The mirror is cooler than the air, but not cold enough to turn the water into ice. The water vapor condensed into liquid drops.
C Soap did not reach the mirror. Water vapor condensed on it.

Q6why

A man walks from a cold street into a warm, crowded café. His eyeglasses fog up at once. Explain where the fog on his glasses came from, using particles.

Starter: The fog came from…

Answer

Model answer · ['the water came from water vapor in the air', 'the cold glasses took energy away from the water vapor particles that hit them', 'the slow particles crowded together as a liquid (condensation)'] points

The fog came from the water vapor in the warm café air.
The glasses are much colder than the air, so heat flows from the air into the glasses.
Cooling takes energy away from the particles.
Water vapor particles that hit the cold glasses slow down.
The slow particles crowd together, touching, so the water vapor condenses into tiny drops on the glasses.

Q7misconception

On a humid summer day, the outside of a toilet's cold water tank is wet. Sam says: "Water is leaking through the tank." Is Sam correct?

A yes
B no

Answer

Key: B — no

The tank is not leaking.
The air holds water vapor.
Water vapor particles that hit the cold tank slow down and crowd together.
The water vapor condenses into drops on the outside of the tank.

Feedback per option

A A wet outside looks like a leak, but the water came from water vapor in the air. The vapor condensed on the cold tank.
B Water vapor in the air condensed on the cold tank, so the water came from the air, not through the tank.

Q8transfer

On a cool morning, drops of water cover the grass in a garden. Nobody watered the grass, and no rain fell. Where did the drops come from?

A from inside the grass blades
B from the soil, pushed up through the blades
C from water vapor in the air

Answer

Key: C — from water vapor in the air

The air holds water vapor.
The grass cooled overnight, so heat flows from the air into the cold blades.
Water vapor particles that hit the cold grass slow down and crowd together.
The water vapor condenses into drops.

Feedback per option

A The grass did not leak. Water vapor in the air condensed on the cold blades.
B The soil did not push water up. Water vapor in the air condensed on the cold blades.
C Water vapor in the air condensed on the cold grass into drops.

Q9fluency

The inside of a tent is covered in drops on a cold morning. Is this condensation or evaporation?

A condensation
B evaporation

Answer

Key: A — condensation

Water vapor in the tent's air turned into liquid drops on the cold fabric.
A gas turning into a liquid is called condensation.

Feedback per option

A A gas turned into a liquid on the cold tent.
B A gas turned into a liquid, not the other way. That is condensation.

Q10fluency

A wet sidewalk dries in the sun. Is this condensation or evaporation?

A condensation
B evaporation

Answer

Key: B — evaporation

The water on the sidewalk turned into a gas from its surface.
A liquid turning into a gas from its surface is called evaporation.

Feedback per option

A A liquid turned into a gas, not the other way. That is evaporation.
B A liquid turned into a gas from its surface.

Q11fluency

A swimmer's wet hair dries in the wind. Is this condensation or evaporation?

A condensation
B evaporation

Answer

Key: B — evaporation

The water in the hair turned into a gas from its surface.
A liquid turning into a gas from its surface is called evaporation.

Feedback per option

A A liquid turned into a gas, not the other way. That is evaporation.
B A liquid turned into a gas from its surface.

Q12fluency

Drops form on the outside of a jug of cold milk on a hot day. Is this condensation or evaporation?

A condensation
B evaporation

Answer

Key: A — condensation

Water vapor in the air turned into liquid drops on the cold jug.
A gas turning into a liquid is called condensation.

Feedback per option

A A gas turned into a liquid on the cold jug.
B A gas turned into a liquid, not the other way. That is condensation.

Your note · lesson 4: Water vapor turns back to liquid

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Lesson 5 of 8Author: definitely a video200 words · about 1:40

Straight from solid to gas

MAT-024 · Sublimation — Distinguish sublimation from melting by identifying which phase change skips the liquid state.

Script

Say	Screen
Here is a block of dry ice in a bowl at a party.	[block in a bowl; label DRY ICE]
Over the evening the block disappears, and the bowl stays dry.	[clock runs; block shrinks to nothing; chip: NO PUDDLE]
Ice leaves a puddle, so where did the dry ice go?	[a second bowl: an ice block becomes a puddle; question mark]
It turned straight into a gas.	[faint gas particles rise from the dry bowl]
When ordinary ice warms, its particles break loose and slide, so it melts into a puddle.	[ice block; solid box becomes liquid box; puddle; label MELTING]
Dry ice is not frozen water but frozen carbon dioxide, the gas we breathe out.	[dry ice block; chip: CARBON DIOXIDE; magnifier: solid box]
When dry ice warms, its particles fly straight off as gas.	[HEAT IN arrow; particles leave the solid grid directly; gas box]
The particles never slide as a liquid, so no puddle forms.	[the liquid box is skipped, crossed out]
A solid turning straight into a gas is called sublimation.	[chip: SUBLIMATION]
To tell melting from sublimation, ask: did a liquid form?	[state map: melting, freezing, evaporation, boiling, condensation, sublimation; chip: DID A LIQUID FORM?]
A snowman shrinks and water runs off: a liquid formed, so it is melting.	[snowman with a puddle; tick under MELTING]
A mothball shrinks for months, nothing wet: no liquid formed, so it is subliming.	[mothball shrinking on a dry shelf; tick under SUBLIMATION]
So, here's what we've seen. Melting is a solid turning into a liquid.	[the rule slide: the state map; the melting arrow highlighted; nothing else printed]
Sublimation is a solid turning straight into a gas, skipping the liquid.	[the sublimation arrow highlighted; the liquid box crossed out]
If a liquid formed, the solid melted; if no liquid ever formed, the solid sublimed.	[chip: DID A LIQUID FORM? with MELTING and SUBLIMATION under yes and no]
So the dry ice flew straight off as gas, and the bowl stayed dry.	[the dry bowl; gas particles above it]
Okay, now your turn.	[the rule slide's images hold; closing screen: bullets — • Melting is a solid turning into a liquid. • Sublimation is a solid turning straight into a gas, skipping the liquid. • If a liquid formed, the solid melted; if no liquid ever formed, the solid sublimed.]

“Okay, now your turn.” — the attached question

video

A block of dry ice shrinks away in a bowl and leaves no puddle. How does it change state?

A straight from solid to gas
B from solid to liquid to gas

Answer

Key: A — straight from solid to gas

The particles fly straight off the solid as a gas.
No liquid forms.
That is sublimation.

Feedback per option

A That is sublimation: the liquid stage is skipped.
B No liquid ever forms.

Quiz after the video — the mastery check, 11 items

Q1recall

What is melting?

A a solid turning into a liquid
B a liquid turning into a gas
C a liquid turning into a solid

Answer

Key: A — a solid turning into a liquid

A solid turning into a liquid is called melting.

Feedback per option

A A solid turning into a liquid is called melting.
B A liquid turning into a gas is evaporation or boiling. Melting is a solid turning into a liquid.
C A liquid turning into a solid is freezing. Melting is a solid turning into a liquid.

Q2recall

How do the particles in a gas move?

A Each particle vibrates on the spot.
B The particles slide past one another.
C The particles fly fast in every direction.

Answer

Key: C — The particles fly fast in every direction.

In a gas the particles are far apart, and they fly fast in every direction.

Feedback per option

A Vibrating on the spot is what particles do in a solid. In a gas the particles fly fast in every direction.
B Sliding past one another is what particles do in a liquid. In a gas the particles fly fast in every direction.
C In a gas the particles fly fast in every direction.

Q3term

What is a solid turning straight into a gas called?

Typed answer

Answer

Accepted: sublimation · subliming · sublime

A solid turning straight into a gas is called sublimation.

Q4term

What is sublimation?

A a solid turning into a liquid, then a gas
B a solid turning straight into a gas
C a gas turning straight into a solid

Answer

Key: B — a solid turning straight into a gas

A solid turning straight into a gas is called sublimation.
No liquid ever forms.

Feedback per option

A A solid turning into a liquid, then a gas, is melting followed by evaporation. Sublimation skips the liquid.
B A solid turning straight into a gas is called sublimation.
C Sublimation runs from solid to gas, not gas to solid.

Q5fluency

A gummy bear left in a pocket on a hot day turns into a sticky liquid. Is this melting or sublimation?

A melting
B sublimation

Answer

Key: A — melting

A liquid formed.
A solid turning into a liquid is called melting.

Feedback per option

A A liquid formed.
B A liquid formed, so the solid melted.

Q6fluency

A solid air freshener in a car shrinks to nothing over a month. Nothing wet ever appears. Is this melting or sublimation?

A melting
B sublimation

Answer

Key: B — sublimation

No liquid ever formed.
A solid turning straight into a gas is called sublimation.

Feedback per option

A No liquid ever formed, so the solid did not melt.
B No liquid ever formed.

Q7fluency

A bag of frozen vegetables left in a freezer for a year has shrunk and dried out. No water ever collected in the bag. Is this melting or sublimation?

A melting
B sublimation

Answer

Key: B — sublimation

No liquid ever formed.
A solid turning straight into a gas is called sublimation.

Feedback per option

A No water ever collected, so the ice in the vegetables did not melt.
B No liquid ever formed.

Q8fluency

An ice sculpture at a wedding slowly turns into a pool of water on the table. Is this melting or sublimation?

A melting
B sublimation

Answer

Key: A — melting

A liquid formed.
A solid turning into a liquid is called melting.

Feedback per option

A A liquid formed.
B A liquid formed, so the solid melted.

Q9fluency

A tub of lip balm left on a sunny windowsill turns runny. Is this melting or sublimation?

A melting
B sublimation

Answer

Key: A — melting

A liquid formed.
A solid turning into a liquid is called melting.

Feedback per option

A A liquid formed.
B A liquid formed, so the solid melted.

Q10fluency

A dark gray solid called iodine is warmed gently in a dish. A purple gas rises from it, and the dish stays dry. Is this melting or sublimation?

A melting
B sublimation

Answer

Key: B — sublimation

No liquid ever formed.
A solid turning straight into a gas is called sublimation.

Feedback per option

A No liquid ever formed, so the solid did not melt.
B No liquid ever formed.

Q11misconception

Frost covers a car windshield on a very cold, dry morning. By noon the frost has gone, and the glass never got wet. Ben says: "The frost melted very fast." Is Ben correct?

A yes
B no

Answer

Key: B — no

Melting makes a liquid.
The glass never got wet, so no liquid ever formed.
The frost particles flew straight off the solid into the air as a gas.
The frost sublimed.

Feedback per option

A Melting makes a liquid, and the glass never got wet. The frost turned straight into a gas: sublimation.
B The glass never got wet, so no liquid formed. The frost turned straight into a gas: sublimation.

Your note · lesson 5: Straight from solid to gas

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Lesson 6 of 8Author: could do without a video200 words · about 1:40

Same substance, different state

MAT-025 · A change of state does not produce a new substance — Explain why melting, freezing, or evaporating a substance does not change what the substance is.

Script

Say	Screen
Here is a candle burning.	[candle with a flame]
Wax near the flame melts and runs down the side.	[runny wax runs down]
At the bottom, the wax cools and hardens into lumps.	[lumps form at the base]
Is the lump still the same wax, and is the melted wax still wax?	[question marks on the lump and the runny wax]
Yes, both are still wax.	[ticks on the lump and the runny wax]
Near the flame, heating gave the wax particles energy.	[magnifier: solid box; HEAT IN arrow]
The same particles broke out of their fixed positions, so the wax melted.	[solid box becomes liquid box; label MELTING]
At the bottom, cooling took energy away from the wax particles.	[HEAT OUT arrow]
The same particles locked back into fixed positions, so the wax froze.	[liquid box becomes solid box; label FREEZING]
Here are the wax particles as a solid, a liquid, and a solid again, side by side.	[three boxes labelled SOLID, LIQUID, SOLID; sixteen particles each]
The particles never changed; only their arrangement and movement changed.	[chips: SAME PARTICLES; ONLY ARRANGEMENT AND MOVEMENT CHANGE]
The same particles make the same substance.	[chip: SAME PARTICLES, SAME SUBSTANCE]
So melted wax is still wax, and hardened wax is still wax.	[label WAX over all three boxes]
Now consider water: ice, liquid water and water vapor are the same particles.	[three boxes labelled ICE, WATER, WATER VAPOR: a solid box, a liquid box, a gas box]
When ice melts or water boils, the same particles only move differently.	[particles animate: vibrate, slide, fly]
Ice is water, liquid water is water, and water vapor is water.	[label WATER over all three boxes]
So, a change of state never makes a new substance.	[the rule slide: the three boxes; chip SAME PARTICLES, SAME SUBSTANCE; nothing else printed]
The same particles are there before and after; only their arrangement and movement change.	[the three boxes; chip ONLY ARRANGEMENT AND MOVEMENT CHANGE]
Okay, now your turn.	[the rule slide's images hold; closing screen: bullets — • A change of state never makes a new substance. • Only the particles' arrangement and movement change.]

“Okay, now your turn.” — the attached question

video

Wax melts and runs down the side of a candle. What is the melted wax?

A still wax
B a new substance

Answer

Key: A — still wax

The wax particles never change.
Only their arrangement and movement change.
Melted wax is still wax.

Feedback per option

A The same particles, arranged and moving differently.
B A change of state never makes a new substance.

Quiz after the video — the mastery check, 10 items

Q1recall

A solid melts. What happens to its particles?

A The particles break out of their fixed positions and slide past one another.
B The particles stop moving.
C The particles turn into different particles.

Answer

Key: A — The particles break out of their fixed positions and slide past one another.

Heating gives the particles energy.
The particles break out of their fixed positions and slide past one another.
The particles themselves do not change.

Feedback per option

A Heating gives the particles energy, and they break loose and slide.
B Particles never stop moving. Heating gives them energy.
C The particles stay the same. Only their arrangement and movement change.

Q2what

A copper wire is melted in a furnace. Is the liquid still copper?

A yes
B no

Answer

Key: A — yes

Solid copper and liquid copper are made of the same copper particles.
Melting changed only the arrangement and the movement of the particles.
So the liquid is still copper.

Feedback per option

A The same copper particles are there; only their arrangement and movement changed.
B Liquid copper looks nothing like the wire, but it is the same copper particles. Melting changed only their arrangement and movement.

Q3what

Rubbing alcohol evaporates from a cloth into the air. Is the gas in the air still rubbing alcohol?

A yes
B no

Answer

Key: A — yes

The gas is made of the same alcohol particles as the liquid.
Evaporation changed only the arrangement and the movement of the particles.
So the gas is still rubbing alcohol.

Feedback per option

A The same alcohol particles are there, now far apart and flying.
B The alcohol seems to have gone, but the same alcohol particles are in the air, now far apart and flying.

Q4why

A jeweler melts a silver spoon, pours the liquid silver into a mold and lets it harden into a ring. Explain why the ring is still silver.

Starter: The ring is still silver because…

Answer

Model answer · ['the particles did not change into different particles', 'melting and freezing changed only how the particles are arranged and how they move', 'the same particles make the same substance, so it is still silver'] points

The ring is still silver because its particles never changed.
When the spoon melted, the same silver particles broke out of their fixed positions and slid.
When the silver hardened, the same particles locked back into fixed positions.
Only the arrangement and the movement of the particles changed.
The same particles make the same substance.

Q5misconception

A wet chalkboard dries after it is wiped. Priya says: "The water has turned into a different substance, water vapor." Is Priya correct?

A yes
B no

Answer

Key: B — no

Water vapor is water as a gas.
The water vapor is made of the same water particles as the liquid water on the board.
Evaporation changed only the arrangement and the movement of the particles.
A change of state never makes a new substance.

Feedback per option

A Water vapor sounds like a new name, but it is water as a gas. The same water particles are there, far apart and flying.
B Water vapor is water as a gas. The same water particles are there, now far apart and flying.

Q6transfer

A carton of frozen orange juice is left out until it thaws into a liquid. What is the liquid?

A a new substance made from the frozen juice
B orange juice
C water that came out of the juice

Answer

Key: B — orange juice

Thawing is melting: a solid turning into a liquid.
The same particles are there before and after.
Only their arrangement and their movement changed.
So the liquid is still orange juice.

Feedback per option

A A change of state never makes a new substance.
B The same particles are there; only their arrangement and movement changed.
C The juice's particles did not separate or change. The whole liquid is orange juice.

Q7fluency

Liquid tin is poured into a mold and hardens into a solid. Is the solid still tin?

A yes
B no

Answer

Key: A — yes

Freezing changed only the arrangement and the movement of the tin particles.
The same particles make the same substance.
So the solid is still tin.

Feedback per option

A The same tin particles are there; only their arrangement and movement changed.
B Hardening looks like a big change, but the same tin particles are there. Freezing changed only their arrangement and movement.

Q8fluency

A jar of peanut oil turns cloudy and solid in a refrigerator. Is the solid still peanut oil?

A yes
B no

Answer

Key: A — yes

Cooling took energy away from the oil particles, and they locked into fixed positions.
The same particles make the same substance.
So the solid is still peanut oil.

Feedback per option

A The same oil particles are there; only their arrangement and movement changed.
B Cloudy and solid looks like a new substance, but the same oil particles are there. Cooling changed only their arrangement and movement.

Q9fluency

Water vapor from a bowl of very hot rice condenses into drops on the lid. Is the liquid on the lid a new substance?

A yes
B no

Answer

Key: B — no

Water vapor is water as a gas.
Condensation changed only the arrangement and the movement of the water particles.
A change of state never makes a new substance.
So the drops are water, not a new substance.

Feedback per option

A The drops look new, but they are water. Condensation changed only the arrangement and the movement of the water particles.
B The drops are water. Condensation changed only the arrangement and the movement of the water particles.

Q10fluency

An iron horseshoe is melted in a furnace. Is the liquid a new substance?

A yes
B no

Answer

Key: B — no

Melting changed only the arrangement and the movement of the iron particles.
A change of state never makes a new substance.
So the liquid is iron, not a new substance.

Feedback per option

A Liquid iron looks nothing like a horseshoe, but it is iron. Melting changed only the arrangement and the movement of the iron particles.
B The liquid is iron. Melting changed only the arrangement and the movement of the iron particles.

Your note · lesson 6: Same substance, different state

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Lesson 7 of 8Author: could do without a video199 words · about 1:40

Mass stays the same when state changes

MAT-026 · State the law of conservation of mass for changes of state — State that the mass of a substance does not change when it changes state.

Script

Say	Screen
Here is a sealed plastic bag of 50 grams of ice on a balance.	[sealed bag of ice on a balance; readout 50 g]
A student leaves the bag on the counter until all the ice has melted.	[clock runs; the ice becomes water inside the bag]
Before she weighs the bag of water, let's work out what the balance will read.	[bag of water on the balance; readout hidden; question mark]
The balance measures the mass of everything in the bag.	[chip: MASS OF EVERYTHING IN THE BAG]
The bag is sealed, so no particle can get out or in.	[magnifier on the seal; chip: NOTHING IN, NOTHING OUT]
Heating gave the ice particles energy, and the ice melted into water.	[solid box becomes liquid box beneath the bag]
Every particle that was in the ice is still in the bag, now as water.	[sixteen particles counted in both boxes]
The particles did not change, and their number did not change.	[chip: SAME PARTICLES, SAME NUMBER]
The same particles have the same mass, so the balance still reads 50 grams.	[readout shows 50 g]
Now consider a sealed jar of melted wax on a balance, reading 80 grams.	[jar of liquid wax on a balance; readout 80 g]
The wax freezes solid; no particle left or arrived, so the balance still reads 80 grams.	[wax turns solid; HEAT OUT arrow; readout stays 80 g]
So, the mass of a substance does not change when it changes state.	[the rule slide: the bag of ice and the bag of water, both at 50 g; nothing else printed]
The same particles are all still there, so the mass is the same before and after.	[sixteen particles counted in both boxes; chip SAME PARTICLES, SAME MASS]
So in the bag, every ice particle is still there as water, and the bag still reads 50 grams.	[the bag of water; readout 50 g beside the earlier 50 g]
Okay, now your turn.	[the rule slide's images hold; closing screen: one line — “The mass of a substance does not change when it changes state.”]

“Okay, now your turn.” — the attached question

video

A sealed bag of ice has a mass of 50 g. The ice melts inside the bag. What is the mass of the bag now?

A less than 50 g
B 50 g
C more than 50 g

Answer

Key: B — 50 g

Every particle that was in the ice is still in the bag as water.
So the mass is still 50 g.

Feedback per option

A No particle leaves the sealed bag.
B Every particle is still in the bag.
C No particle arrives.

Quiz after the video — the mastery check, 10 items

Q1recall

A substance changes state. Are its particles the same particles before and after?

A yes
B no

Answer

Key: A — yes

A change of state never makes a new substance.
The same particles are there before and after.
Only their arrangement and their movement change.

Feedback per option

A The same particles are there before and after. Only their arrangement and movement change.
B A change of state looks like a change of stuff, but the same particles are there before and after. Only their arrangement and movement change.

Q2recall

Which bag has more mass?

A the pasta
B the rice
C they have the same mass

Answer

Key: B — the rice

A bigger reading on the balance means more mass.
The rice reads 800 g and the pasta reads 500 g.
So the rice has more mass.

Feedback per option

A A bigger balance reading means more mass, and the rice reads more.
B A bigger balance reading means more mass.
C The two bags read differently, so their masses differ.

Q3what

A sealed bottle of water is put in a freezer. All the water turns to ice. What happens to the mass of the bottle and its contents?

A The mass goes up.
B The mass goes down.
C The mass stays the same.

Answer

Key: C — The mass stays the same.

The bottle is sealed, so no particle left and no particle arrived.
Freezing changed only the arrangement and the movement of the particles.
The same particles have the same mass.
So the mass stays the same.

Feedback per option

A No particle arrived. The same particles are there, so the mass is the same.
B No particle left the sealed bottle. The same particles are there, so the mass is the same.
C The same particles are all still there, so the mass does not change.

Q4why

A sealed jar holds 120 g of solid coconut oil. In a hot room all the oil turns liquid, and the jar still reads 120 g. Explain why the mass did not change.

Starter: The mass did not change because…

Answer

Model answer · ['the jar is sealed, so no particle left or arrived', 'melting changed only how the particles are arranged and move', 'the same particles have the same mass'] points

The mass did not change because the jar is sealed.
No particle left the jar, and no particle arrived.
Melting changed only the arrangement and the movement of the oil particles.
Every particle that was in the solid oil is still in the jar as liquid oil.
The same particles have the same mass.

Q5misconception

A sealed plastic bottle of frozen root beer is left in the sun until the root beer is liquid again. Leo says: "The bottle has the same mass, because the same particles are still inside it." Is Leo correct?

A yes
B no

Answer

Key: A — yes

The bottle is sealed, so no particle left and no particle arrived.
Every root beer particle is still in the bottle, now as a liquid.
The same particles have the same mass.
So the mass is the same, just as Leo says.

Feedback per option

A Every root beer particle is still in the sealed bottle, now as a liquid, so the mass is the same.
B Melting changes how the root beer looks, not how much there is. Every particle is still in the sealed bottle, so the mass is the same.

Q6transfer

A sealed tub of solid butter reads 250 g. In a warm room all the butter melts. What does the balance read now?

A less than 250 g
B 250 g
C more than 250 g

Answer

Key: B — 250 g

The tub is sealed, so no particle left and no particle arrived.
Every butter particle is still in the tub, now as a liquid.
The same particles have the same mass.
So the balance still reads 250 g.

Feedback per option

A No particle left the sealed tub. The same particles have the same mass.
B The same particles are all still there, so the mass is the same.
C No particle arrived in the sealed tub. The same particles have the same mass.

Q7fluency

A sealed pouch of applesauce is frozen solid. Compared with before, what is the mass of the pouch and its contents now?

A less mass
B the same mass
C more mass

Answer

Key: B — the same mass

The pouch is sealed, so no particle left and no particle arrived.
Freezing changed only the arrangement and the movement of the particles.
The same particles have the same mass.

Feedback per option

A No particle left the sealed pouch. The same particles have the same mass.
B The same particles are all still in the pouch, so the mass is the same.
C No particle arrived in the sealed pouch. The same particles have the same mass.

Q8fluency

A sealed glass flask holds water vapor. The flask cools, and the water vapor condenses into drops inside it. Does the mass of the flask and its contents change?

A yes
B no

Answer

Key: B — no

The flask is sealed, so no particle left and no particle arrived.
Condensation changed only the arrangement and the movement of the water particles.
The same particles have the same mass.
So the mass does not change.

Feedback per option

A Drops look heavier than vapor, but they are the same water particles. Every particle is still in the sealed flask, so the mass is the same.
B Every water particle is still inside the sealed flask, now as a liquid, so the mass is the same.

Q9fluency

A sealed tub of ice cream is weighed, left to melt in a warm car, and weighed again. Which reading is bigger?

A the first reading, before melting
B the second reading, after melting
C neither reading

Answer

Key: C — neither reading

The tub is sealed, so no particle left and no particle arrived.
Every ice cream particle is still in the tub, now as a liquid.
The same particles have the same mass.
So both readings are the same.

Feedback per option

A No particle left the sealed tub, so the mass did not go down.
B No particle arrived in the sealed tub, so the mass did not go up.
C The same particles are in the tub before and after, so both readings are the same.

Q10fluency

A sealed bottle of vinegar is left in a freezer until the vinegar is solid. Nadia says: "The bottle has more mass now, because a solid has more mass than a liquid." Is Nadia correct?

A yes
B no

Answer

Key: B — no

The bottle is sealed, so no particle left and no particle arrived.
Freezing changed only the arrangement and the movement of the vinegar particles.
The same particles have the same mass.
So the mass did not go up.

Feedback per option

A A solid has no more mass than the same liquid. The same vinegar particles are in the sealed bottle before and after, so the mass is the same.
B The same vinegar particles are in the sealed bottle before and after, so the mass is the same.

Your note · lesson 7: Mass stays the same when state changes

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Lesson 8 of 8Author: could do without a video199 words · about 1:40

Work out the mass after a change of state

MAT-026b · Apply conservation of mass during a change of state — Calculate the mass of a substance after a change of state given its mass before.

Script

Say	Screen
Here is a sealed bag of ice on a balance. The balance reads 45 grams.	[sealed bag of ice on a balance; readout 45 g]
The ice melts inside the bag.	[the ice becomes water]
A student is asked for the mass of the water, but she has not weighed it.	[balance grayed out; question mark]
Can she still give the answer?	[chip: CAN SHE ANSWER?]
Yes, she can.	[tick]
The mass of a substance does not change when it changes state.	[chip: MASS DOES NOT CHANGE]
The bag is sealed, so every ice particle is still there as water.	[sixteen particles: grid becomes a jumbled liquid layer along the floor]
So the mass of the water equals the mass of the ice: 45 grams.	[line: mass after melting = mass before melting = 45 g]
The bag held 45 grams of ice. The ice melted while sealed, so the bag holds 45 grams of water.	[table: before, change, after; cells fill in turn]
Now consider an open pan holding 500 grams of water.	[open pan on a burner; label 500 g]
The water boils, and 200 grams leaves as water vapor.	[vapor particles rise out of the pan; label 200 g leaves]
So the mass left is the mass before minus the mass that escaped.	[line: mass left = mass before − mass escaped]
500 grams minus 200 grams leaves 300 grams.	[lines: mass left = 500 g − 200 g; mass left = 300 g]
So, when a substance changes state, its mass after equals its mass before.	[the rule slide: the before-change-after table; nothing else printed]
If some of the substance escapes as a gas, the mass left is the mass before minus the mass that escaped.	[the open pan; the line mass left = mass before − mass escaped]
So in the bag, the mass does not change, and the water is 45 grams.	[the bag of water; 45 g]
Okay, now your turn.	[the rule slide's images hold; closing screen: bullets — • When a substance changes state, its mass after equals its mass before. • If some escapes as a gas, the mass left is the mass before minus the mass that escaped.]

“Okay, now your turn.” — the attached question

video

45 g of ice melts inside a sealed bag. What is the mass of the water, in grams?

Typed answer

Answer

Accepted: 45 · 45 g · 45 grams

The mass does not change when a substance changes state.
45 g of ice becomes 45 g of water.

Quiz after the video — the mastery check, 10 items

Q1recall

A substance changes state inside a sealed container. What happens to its mass?

A The mass goes up.
B The mass stays the same.
C The mass goes down.

Answer

Key: B — The mass stays the same.

The mass of a substance does not change when it changes state.
The same particles are all still there.

Feedback per option

A No particle arrived, so the mass cannot go up.
B The same particles are all still there, so the mass does not change.
C No particle left, so the mass cannot go down.

Q2scaffold

A sealed bag holds 120 g of water. The bag is put in a freezer at −18 °C until all the water is ice. What is the mass of the ice, in grams?

Typed answer

Answer

Accepted: 120 · 120 g · 120 grams

Mass of ice = mass of water = 120 g. The bag is sealed, so the mass does not change.

Q3scaffold

A sealed can holds 200 g of solid cooking fat. The can sits by a warm stove until all the fat is liquid. What is the mass of the liquid fat, in grams?

Typed answer

Answer

Accepted: 200 · 200 g · 200 grams

Mass of liquid fat = mass of solid fat = 200 g. The can is sealed, so the mass does not change.

Q4scaffold

An open pot of soup boils on a stove, and some of the water in it leaves as water vapor. Does the mass of soup in the pot stay the same?

A yes
B no

Answer

Key: B — no

Some water particles left the open pot as water vapor.
Those particles are in the air, not in the pot.
So the mass of soup in the pot went down.

Feedback per option

A The particles that left as water vapor are in the air now, not in the pot, so the mass in the pot went down.
B The particles that left as water vapor are in the air now, so the mass in the pot went down.

Q5scaffold

An open kettle holds 800 g of water. The water boils, and 150 g of it leaves the kettle as water vapor. What mass of water is left in the kettle, in grams?

Typed answer

Answer

Accepted: 650 · 650 g · 650 grams

Mass left = mass before − mass escaped = 800 g − 150 g = 650 g.

Q6bare

A sealed bottle holds 330 g of fruit juice. The bottle is frozen solid. What is the mass of the frozen juice, in grams?

Typed answer

Answer

Accepted: 330 · 330 g · 330 grams

Mass of frozen juice = mass of liquid juice = 330 g. The bottle is sealed, so the mass does not change.

Q7bare

An open saucepan holds 600 g of milk. The milk is heated until it boils, and 100 g of water leaves it as water vapor. What mass of milk is left in the saucepan, in grams?

Typed answer

Answer

Accepted: 500 · 500 g · 500 grams

Mass left = mass before − mass escaped = 600 g − 100 g = 500 g.

Q8fluency

A sealed bag holds 350 g of frozen strawberries. The strawberries thaw completely inside the bag. What is the mass of the thawed strawberries, in grams?

Typed answer

Answer

Accepted: 350 · 350 g · 350 grams

Mass of thawed strawberries = mass of frozen strawberries = 350 g. The bag is sealed, so the mass does not change.

Q9fluency

An open fish tank holds 9000 g of water. Over a month, 700 g of the water evaporates into the air. What mass of water is left in the tank, in grams?

Typed answer

Answer

Accepted: 8300 · 8300 g · 8300 grams · 8,300 · 8,300 g

Mass left = mass before − mass escaped = 9000 g − 700 g = 8300 g.

Q10fluency

An open pan holds 800 g of tomato sauce. The sauce boils, and 250 g of water leaves it as water vapor. What mass of sauce is left in the pan, in grams?

Typed answer

Answer

Accepted: 550 · 550 g · 550 grams

Mass left = mass before − mass escaped = 800 g − 250 g = 550 g.

Your note · lesson 8: Work out the mass after a change of state

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Summary video · everything taught, in order, just before the PP100251 words · about 2:06

Summary: Changing state

Script, part 1 (84 words)

Say	Screen
Here is everything we found out about changing state.	[a still: the ice cube, the puddle and the cold can]
Heating gives particles energy; cooling takes it away.	[chips: HEATING GIVES ENERGY; COOLING TAKES ENERGY AWAY]
The particles in a solid vibrate harder, break out of their fixed positions and slide past one another. The solid melts into a liquid.	[the melting panels; chip MELTING]
A solid turning into a liquid is called melting.	[chip: MELTING]
The particles in a liquid slow down, stop sliding and lock into fixed positions.	[the freezing panels]
The liquid freezes into a solid, and a liquid turning into a solid is called freezing.	[chip: FREEZING]
Okay, now your turn.	[the melting and freezing panels hold]

“Okay, now your turn.” — the check question between the parts

video

What is a solid turning into a liquid called?

A melting
B freezing
C boiling

Answer

Key: A — melting

A solid turning into a liquid is called melting.

Feedback per option

A Melting is a solid turning into a liquid.
B Freezing is a liquid turning into a solid.
C Boiling is a liquid turning into a gas all through the liquid.

Script, part 2 (167 words)

Say	Screen
Here is everything we found out about turning into a gas, and back.	[a still: the puddle, the pan and the can]
Water as a gas is called water vapor.	[chip: WATER VAPOR]
The fastest particles at the surface of a liquid fly off as a gas: that is evaporation.	[the puddle; particles leave its surface; chip EVAPORATION]
At 100 degrees Celsius, water particles fly off all through the liquid as bubbles of water vapor: that is boiling.	[the pan; bubbles rise; chip BOILING]
Gas particles that touch a cold surface slow down and crowd together, touching and sliding. The gas condenses into a liquid.	[the can with drops; chip CONDENSATION]
A gas turning into a liquid is called condensation.	[chip: CONDENSATION]
Sublimation is a solid turning straight into a gas, skipping the liquid.	[the state map; the sublimation arrow highlighted]
If a liquid formed, the solid melted; if no liquid ever formed, the solid sublimed.	[chip: DID A LIQUID FORM?]
A change of state never makes a new substance. Only the particles' arrangement and movement change.	[three boxes, sixteen particles each; chip SAME SUBSTANCE]
So the mass of a substance does not change when it changes state.	[sealed bag on the balance: 50 g, 50 g]
If some escapes as a gas, the mass left behind is the mass before minus the mass that escaped.	[open pan; the line mass left = mass before − mass escaped]
Okay, now your turn.	[the state map holds]

“Okay, now your turn.” — the two questions after part 2

video

Which change of state goes straight from solid to gas?

A melting
B boiling
C sublimation

Answer

Key: C — sublimation

Sublimation is a solid turning straight into a gas.

Feedback per option

A Melting is solid to liquid.
B Boiling is liquid to gas.
C Sublimation skips the liquid altogether.

video

A sealed jar of melted wax has a mass of 80 g. The wax freezes solid. What is its mass now?

A less than 80 g
B 80 g
C more than 80 g

Answer

Key: B — 80 g

The mass of a substance does not change when it changes state.
So the wax is still 80 g.

Feedback per option

A No particle leaves the sealed jar.
B The same particles are all still there, so the mass is the same.
C No particle arrives.

Your note · the summary video

What to judge

Is this content better than the current alternative students have (PhysicsGraph / Edmentum)?

8/10 on:

Clear and concise language
Physics accuracy (read as chemistry accuracy here; his line as pasted for HS Physics)
No "clangers" (content that causes a problematic misconception)
Appropriate questions
Initial testing
Expansion into harder questions (no exam)
The tasks should use similar language to that of the lesson

Gut check: better than the alternative? Would a student benefit? Full criteria

Applied without asking

Rulings you have already given; in force on every card above, not re-asked.

Every video ends “Okay, now your turn.” with one easy, video-dependent question (the XP gate).
An intro video is at most 120 words and teaches nothing: it opens the question the topic answers.
A summary video is at most 300 words: everything taught, in order, just before the PP100.
A lesson script is at most 200 words.
Each lesson ships as both a video and an article; the article is not under review here.

The topic’s fixed wording (the lexicon the scripts repeat)

In a solid the particles are packed tightly, touching, in fixed positions. Each particle vibrates on the spot.
In a liquid the particles touch but have no fixed positions. They slide past one another.
In a gas the particles are far apart with empty space between them. They fly fast in every direction.
Heating makes particles move faster. Cooling makes them move more slowly.
Heating gives particles energy; cooling takes it away.

Scripts, questions and quizzes are read from the course content as it stands today; the student site for this topic is here.