Topic 5 · Pure substances and mixtures — 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, 5 lesson videos (4 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.
Introduction: Pure substances and mixtures
Script
| Say | Screen |
|---|---|
| Here is a student at a bench with three samples: a glass of water, a glass of orange juice, and a bowl of sand with salt stirred in. | [a bench; the student; the two glasses and the bowl in a row] |
| After an hour, the water looks the same all through, but the juice has settled into layers. | [a clock sweeps; the juice settles; the water stays even] |
| The sand and salt make one gray heap that looks like one thing. | [the bowl; one gray heap] |
| So how many kinds of matter are in each sample, and how are they spread? | [question mark over the three samples; a zoom circle hovers, not yet zoomed] |
| To find out, we will zoom in on the particles in each sample, and sort samples by what we see. | [the three samples stay] |
| Okay, so are you ready to zoom in and find out how many kinds of matter are in a glass of juice? | [the three replies appear] |
The ready line's poll — the attached item (no key; the intro teaches nothing)
Okay, so are you ready to zoom in and find out how many kinds of matter are in a glass of juice?
- A Yes, let's go! — Great. Here we go.
- B Not sure yet — That's fine. We take it one sample 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.
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
One kind of matter: a pure substance
MAT-027 · Pure substance — Identify which samples are pure substances based on whether they contain only one kind of matter.
Script
| Say | Screen |
|---|---|
| A student pours a glass of distilled water, the kind sold for steam irons, and a glass of orange juice. | [two glasses side by side; labels DISTILLED WATER, ORANGE JUICE] |
| After an hour the water is the same all through, but the juice has settled, with pulp at the bottom. | [a clock hand sweeps one hour; the water glass even all through; the juice glass with a pulp layer] |
| What is different about the water? | [question mark over the water glass] |
| The water holds only one kind of matter. | [chip over the water glass: ONE KIND OF MATTER] |
| All matter is made of particles that are far too small to see. | [a zoom circle opens on the water] |
| Zoomed in, every particle in the distilled water is a water particle. | [sample box: sixteen filled circles; legend WATER PARTICLES] |
| Zoomed in, the juice holds water particles, sugar particles and pulp, all mingled. | [sample box: filled and open circles mingled; legend WATER, SUGAR, AND MORE] |
| A sample that contains only one kind of matter is called a pure substance. | [chip: PURE SUBSTANCE] |
| The distilled water is a pure substance, and the juice is not. | [tick on the water box; cross on the juice box] |
| In a copper wire, every particle is a copper particle, so the wire is a pure substance. | [copper wire; box of filled circles; tick] |
| In table sugar, every particle is a sugar particle, so sugar is a pure substance. | [sugar; box of filled circles; tick] |
| Sea water looks as clear, but it holds water particles and salt particles. | [clear sea water; box with filled and open circles; cross] |
| That is two kinds of matter, so sea water is not a pure substance. | [verdict: NOT A PURE SUBSTANCE] |
| So, here's what we've seen. A sample that contains only one kind of matter is called a pure substance. | [the rule slide: the water box and the sea water box with their tick and cross; chip PURE SUBSTANCE; nothing else printed] |
| Okay, now your turn. | [the rule slide's images hold; closing screen: one line — “A sample that contains only one kind of matter is called a pure substance.”] |
“Okay, now your turn.” — the attached question
Sea water looks as clear as distilled water, but zoomed in it holds water particles and salt particles. Is sea water a pure substance?
- A Yes, it is a pure substance.
- B No, it is not a pure substance.
Answer
Key: B — No, it is not a pure substance.
Sea water holds water particles and salt particles: two kinds.
So sea water is not a pure substance, however clear it looks.
Feedback per option
- A Two kinds of particle mingled means more than one kind of matter.
- B Water particles and salt particles are two kinds of matter, so sea water is not a pure substance.
Quiz after the video — the mastery check, 12 items
A pinch of cinnamon is made of particles far too small to see. True or false?
- A true
- B false
Answer
Key: A — true
Cinnamon is matter.
So a pinch of cinnamon is made of particles too.
Feedback per option
- A All matter is made of particles that are far too small to see, cinnamon included.
- B Cinnamon is matter, and all matter is made of particles far too small to see.
A sample that contains only one kind of matter is called a…
Typed answer
Answer
Accepted: pure substance · a pure substance
A scientist calls a sample a pure substance. What does she mean?
- A The sample contains only one kind of matter.
- B The sample is clean, with no dirt in it.
- C The sample is clear enough to see through.
Answer
Key: A — The sample contains only one kind of matter.
Zoom in, and every particle is the same kind.
Clean and clear are different ideas.
Feedback per option
- A Zoom in, and every particle is the same kind.
- B Pure here means one kind of matter only, not clean.
- C Pure here means one kind of matter only, not clear.
Filled and open circles are two different kinds of particle. Is this sample a pure substance?
- A yes
- B no
Answer
Key: A — yes
Every circle is filled, so every particle is the same kind.
One kind of matter only makes a pure substance.
Feedback per option
- A Every particle in the box is the same kind, so the sample is a pure substance.
- B Every circle is filled, so every particle is the same kind.
Filled and open circles are two different kinds of particle. Is this sample a pure substance?
- A yes
- B no
Answer
Key: B — no
Filled circles and open circles are two kinds of particle.
More than one kind of matter, so the sample is not a pure substance.
Feedback per option
- A Filled circles and open circles are two kinds of particle.
- B Two kinds of particle are mingled, so the sample is not a pure substance.
A pizza: dough, tomato sauce and cheese. Is the pizza a pure substance?
- A yes
- B no
Answer
Key: B — no
Those are several kinds of matter.
So the pizza is not a pure substance.
Feedback per option
- A Dough, sauce and cheese are several kinds of matter.
- B Several kinds of matter together, so the pizza is not a pure substance.
Aluminum foil: every particle in it is an aluminum particle. Is the foil a pure substance?
- A yes
- B no
Answer
Key: A — yes
The foil holds one kind of matter only.
So the foil is a pure substance.
Feedback per option
- A One kind of particle only, so the foil is a pure substance.
- B Every particle is an aluminum particle, so the foil holds one kind of matter.
Soda: water, sugar and gas particles mingled. Is the soda a pure substance?
- A yes
- B no
Answer
Key: B — no
Those are three kinds of matter.
So the soda is not a pure substance.
Feedback per option
- A Water, sugar and gas particles are three kinds of matter.
- B Three kinds of particle mingled, so the soda is not a pure substance.
Filled and open circles are two different kinds of particle. Is this sample a pure substance?
- A yes
- B no
Answer
Key: B — no
Filled circles fill most of the box, and open circles sit along the bottom: two kinds.
More than one kind of matter, so the sample is not a pure substance.
Feedback per option
- A The open circles along the bottom are a second kind of particle.
- B Two kinds of particle are in the box, so the sample is not a pure substance.
An ice cube: every particle in it is a water particle. Is the ice cube a pure substance?
- A yes
- B no
Answer
Key: A — yes
The ice cube holds one kind of matter only.
So the ice cube is a pure substance.
Feedback per option
- A One kind of particle only, so the ice cube is a pure substance.
- B Every particle is a water particle, so the ice cube holds one kind of matter.
Steam from a kettle: every particle is a water particle. Is the steam a pure substance?
- A yes
- B no
Answer
Key: A — yes
The steam holds one kind of matter only.
So the steam is a pure substance, just as the water was.
Feedback per option
- A One kind of particle only, so the steam is a pure substance.
- B Every particle is a water particle, so the steam holds one kind of matter.
Rafael looks at a glass of clear sugar water. He says: "It looks the same all the way through, so it is a pure substance." Is Rafael correct?
- A yes
- B no
Answer
Key: B — no
Zoom in on the sugar water: sugar particles and water particles are mingled.
Two kinds of matter, so sugar water is not a pure substance, and Rafael is not correct.
Feedback per option
- A Looking the same all through is not the test. Zoom in: sugar particles and water particles are two kinds, so sugar water is not pure.
- B Sugar water holds sugar particles and water particles, two kinds of matter, so it is not a pure substance.
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
More than one kind: a mixture
MAT-028 · Mixture — Classify a sample as a pure substance or a mixture based on whether it contains more than one substance.
Script
| Say | Screen |
|---|---|
| A student pours salt into a bowl of sand and stirs. | [a bowl of sand; salt pours in; a spoon stirs] |
| The bowl now holds one gray-white heap that looks like one material. | [the heap; label ONE HEAP?] |
| Under a magnifying glass, she still sees salt grains and sand grains side by side. | [magnifying glass: clear grains and dark grains] |
| Is the heap one kind of matter, or two? | [question mark] |
| It is two kinds of matter. | [chip: TWO KINDS] |
| Salt on its own is a pure substance: every particle is a salt particle. | [box of filled circles labeled SALT] |
| Zoomed in, salt particles and sand particles sit side by side in the heap, each still itself. | [sample box in clumps: filled sand particles and open salt particles, salt grains here and sand grains there] |
| A sample that contains two or more substances mingled together is called a mixture. | [chip: MIXTURE] |
| Stirring does not turn two substances into one; each keeps its own particles. | [the spoon stirs; the two kinds stay two kinds] |
| Trail mix is nuts, raisins and seeds in one bowl, so trail mix is a mixture you can see. | [bowl of trail mix; tick] |
| Distilled water is one kind of particle only, so it is a pure substance, not a mixture. | [box of filled circles; cross] |
| Air holds several gases mingled together, so air is a mixture you cannot see. | [box with filled and open circles labeled AIR; tick] |
| So, here's what we've seen. A sample that contains two or more substances mingled together is called a mixture. | [the rule slide: the heap box and the trail mix; chip MIXTURE; nothing else printed] |
| So the heap is a mixture. | [the heap box; verdict A MIXTURE] |
| Okay, now your turn. | [the rule slide's images hold; closing screen: one line — “A sample that contains two or more substances mingled together is called a mixture.”] |
“Okay, now your turn.” — the attached question
A student stirs salt into a bowl of sand and zooms in on the heap. What does the zoom show?
- A one new kind of particle, made by stirring
- B two kinds of particle, side by side
Answer
Key: B — two kinds of particle, side by side
The zoom shows salt particles and sand particles side by side.
Two substances mingled together make a mixture.
Feedback per option
- A Stirring does not turn two substances into one.
- B Salt particles and sand particles sit side by side, each still itself: a mixture.
Quiz after the video — the mastery check, 12 items
A diamond: every particle in it is the same kind. Is the diamond a pure substance?
- A yes
- B no
Answer
Key: A — yes
Every particle in the diamond is the same kind.
So the diamond is a pure substance.
Feedback per option
- A One kind of particle only, so the diamond is a pure substance.
- B Every particle is the same kind, so the diamond holds one kind of matter.
A sample that contains two or more substances mingled together is called a…
Typed answer
Answer
Accepted: mixture · a mixture
What is a mixture?
- A two or more substances mingled together
- B one kind of matter only
- C a new substance made by stirring two substances together
Answer
Key: A — two or more substances mingled together
Each substance keeps its own particles.
Stirring does not turn two substances into one.
Feedback per option
- A Each substance in a mixture keeps its own particles.
- B One kind of matter only is a pure substance, not a mixture.
- C Stirring does not make a new substance. Each substance keeps its own particles.
Filled and open circles are two different kinds of particle. Pure substance or mixture?
- A a pure substance
- B a mixture
Answer
Key: B — a mixture
Filled circles and open circles are two kinds of particle, mingled.
Two or more substances mingled together make a mixture.
Feedback per option
- A Filled circles and open circles are two kinds of particle.
- B Two kinds of particle mingled together make a mixture.
Granola: oats, nuts and dried fruit stirred together. Pure substance or mixture?
- A a pure substance
- B a mixture
Answer
Key: B — a mixture
Those are three substances, mingled together.
So granola is a mixture.
Feedback per option
- A Oats, nuts and dried fruit are three substances.
- B Three substances mingled together make a mixture.
A silver spoon: every particle in it is a silver particle. Pure substance or mixture?
- A a pure substance
- B a mixture
Answer
Key: A — a pure substance
The spoon holds one kind of matter only.
So the spoon is a pure substance, not a mixture.
Feedback per option
- A Every particle is the same kind, so the spoon is a pure substance.
- B A mixture needs two or more substances. The spoon holds one kind of particle only.
Filled and open circles are two different kinds of particle. Pure substance or mixture?
- A a pure substance
- B a mixture
Answer
Key: A — a pure substance
Every circle is filled, so every particle is the same kind.
One kind of matter only makes a pure substance.
Feedback per option
- A Every circle is filled, so every particle is the same kind.
- B A mixture needs two kinds of particle. Every circle here is filled: one kind.
Vegetable soup: broth, carrots, peas and beans. Pure substance or mixture?
- A a pure substance
- B a mixture
Answer
Key: B — a mixture
Those are four substances, mingled together.
So the soup is a mixture.
Feedback per option
- A Broth, carrots, peas and beans are four substances.
- B Four substances mingled together make a mixture.
Sweet tea: water particles, tea particles and sugar particles mingled. Pure substance or mixture?
- A a pure substance
- B a mixture
Answer
Key: B — a mixture
Those are three substances, mingled together.
So sweet tea is a mixture.
Feedback per option
- A Water, tea and sugar particles are three kinds of particle.
- B Three kinds of particle mingled together make a mixture.
An iron nail: every particle is an iron particle. Pure substance or mixture?
- A a pure substance
- B a mixture
Answer
Key: A — a pure substance
The nail holds one kind of matter only.
So the nail is a pure substance, not a mixture.
Feedback per option
- A Every particle is the same kind, so the nail is a pure substance.
- B A mixture needs two or more substances. The nail holds one kind of particle only.
Filled and open circles are two different kinds of particle. Pure substance or mixture?
- A a pure substance
- B a mixture
Answer
Key: B — a mixture
Open circles sit along the top, and filled circles fill the rest: two kinds.
Two substances in one sample make a mixture.
Feedback per option
- A The open circles along the top are a second kind of particle.
- B Two kinds of particle in one sample make a mixture, wherever each kind sits.
Idris stirs sesame seeds into a bowl of rice. He says: "Now the seeds and the rice have become one new substance." Is Idris correct?
- A yes
- B no
Answer
Key: B — no
Each substance keeps its own particles: the seeds are still seeds, and the rice is still rice.
Two substances mingled together make a mixture, so Idris is not correct.
Feedback per option
- A Stirring does not turn two substances into one. The seeds are still seeds and the rice is still rice, so the bowl holds a mixture.
- B The seeds are still seeds and the rice is still rice, so the bowl holds a mixture.
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
A mixture can be taken apart
MAT-029 · Mixtures can be separated by physical means — State that the components of a mixture can be separated because each keeps its own properties.
Script
| Say | Screen |
|---|---|
| A student spills iron filings into a tray of sand. | [a tray of sand; dark filings scatter into it] |
| Picking the filings out one by one would take all day. | [a hand with tweezers; a clock] |
| She holds a magnet just above the tray. | [a bar magnet lowers over the tray] |
| The filings jump up onto the magnet, and the sand stays in the tray. | [filings fly up and cling to the magnet; the sand stays] |
| Why could the magnet pull one part out and leave the other? | [question mark] |
| The iron stayed magnetic in the tray, and the sand did not. | [chip: IRON STILL MAGNETIC] |
| The tray holds iron filings and sand mingled together, so it is a mixture. | [chip: A MIXTURE] |
| Zoomed in, iron particles and sand particles sit side by side, each still itself. | [sample box in clumps: filled sand particles, open iron particles gathered in small clumps, each kind still itself] |
| Iron on its own is magnetic; sand on its own is not. | [a magnet over iron: pulls; over sand: nothing] |
| In the mixture, the iron is still magnetic, and the sand is still not. | [the same two tests inside the tray] |
| So in a mixture, each substance keeps its own properties. | [chip: EACH PART KEEPS ITS OWN PROPERTIES] |
| The magnet pulls on the iron and not on the sand, so it lifts only the iron. | [the filings rise to the magnet; the sand stays] |
| Other mixtures come apart the same way: in water, sawdust floats and gravel sinks. | [bucket: sawdust on top, gravel on the bottom] |
| And from sugar water, the water evaporates, but the sugar stays. | [dish; the water leaves as a gas; sugar grains remain] |
| Here's the pattern. In a mixture each substance keeps its own properties, so the parts of a mixture can be separated. | [the rule slide: the tray and the magnet with its filings; chip EACH PART KEEPS ITS OWN PROPERTIES; nothing else printed] |
| Okay, now your turn. | [the rule slide's images hold; closing screen: one line — “In a mixture each substance keeps its own properties, so the parts of a mixture can be separated.”] |
“Okay, now your turn.” — the attached question
A magnet held over a tray of sand and iron filings lifts the filings and leaves the sand. Why?
- A The iron is still magnetic; the sand is not.
- B The magnet pulls on anything small enough.
- C The sand is stuck to the bottom of the tray.
Answer
Key: A — The iron is still magnetic; the sand is not.
The iron is still magnetic, and the sand is still not.
So the magnet pulls on the iron only.
Feedback per option
- A Each part keeps its own properties: the iron is still magnetic, the sand still not.
- B A magnet pulls on magnetic materials only, whatever their size.
- C The sand stays because the magnet does not pull on sand, not because it is stuck.
Quiz after the video — the mastery check, 10 items
Breakfast cereal with milk poured over it. Mixture or pure substance?
- A a mixture
- B a pure substance
Answer
Key: A — a mixture
Two or more substances mingled together make a mixture.
So the cereal with milk is a mixture.
Feedback per option
- A Cereal and milk are two substances mingled together.
- B A pure substance is one kind of matter only. Cereal and milk are two.
Steel paper clips and plastic beads are shaken together in a jar. Steel is magnetic; plastic is not. What does a magnet held over the jar lift out?
- A the paper clips only
- B the beads only
- C both the clips and the beads
- D neither
Answer
Key: A — the paper clips only
The paper clips are still steel, so they are still magnetic.
The beads are still plastic, so they are still not magnetic.
The magnet pulls on the clips only, so the clips lift out.
Feedback per option
- A The clips are still steel, so still magnetic. The beads are still plastic, so still not.
- B The beads are plastic, and plastic is not magnetic.
- C Only the steel clips are magnetic. The plastic beads are not.
- D The steel clips are still magnetic in the mixture, so the magnet lifts them.
A magnet lifts steel paper clips out of a jar of plastic beads and leaves the beads behind. Steel is magnetic; plastic is not. Explain why the magnet can separate the clips from the beads.
Starter: The magnet can separate the clips from the beads because…
Answer
Model answer · ['each substance keeps its own properties in the mixture', 'the steel clips are still magnetic, and the plastic beads are still not', 'the magnet pulls on the clips only, so the clips lift out and the beads stay'] points
The paper clips are still steel, so they are still magnetic.
The beads are still plastic, so they are still not magnetic.
The magnet pulls on the paper clips and not on the beads.
So the paper clips lift out and the beads stay behind.
Why can the parts of a mixture be separated?
- A The parts of a mixture are always different sizes.
- B The parts of a mixture always have different colors from each other.
- C Each substance keeps its own properties in the mixture.
Answer
Key: C — Each substance keeps its own properties in the mixture.
A property that one part has and the other part lacks lets you pull the parts apart.
So the parts of a mixture can be separated.
Feedback per option
- A Size is one property, and many mixtures have parts of one size. Each part keeps all its own properties.
- B Color is only one property, and many mixtures are one color. Each part keeps all its own properties.
- C A property that one part has and the other lacks lets you pull them apart.
Amira stirs salt into a pot of soup until the salt disappears. She says: "The salt and the soup are one new substance now, so the salt can never be taken back out." Is Amira correct?
- A yes
- B no
Answer
Key: B — no
The salt is still salt: the soup tastes salty.
Each substance keeps its own properties in a mixture, so the parts can be separated, and Amira is not correct.
Feedback per option
- A Disappearing is not becoming one substance. The salt is still salt, so the soup tastes salty, and the salt can be taken back out.
- B The salt is still salt: the soup tastes salty. Each substance keeps its own properties in a mixture, so the salt can be taken back out.
Dried pasta and ground pepper are shaken together in a sieve with small holes. Which falls through the holes?
- A the pasta
- B the pepper
- C both the pasta and the pepper
Answer
Key: B — the pepper
The pepper grains are tiny, so they fall through the holes.
The pasta pieces are big, so they stay in the sieve.
Feedback per option
- A Pasta pieces are far bigger than the holes.
- B Pepper grains are tiny, so they fall through. Pasta pieces are big, so they stay.
- C Only the tiny pepper grains fit through the holes.
Cork pieces and glass beads are stirred into a bucket of water. Cork floats in water; glass sinks. Which floats up to the top?
- A the glass beads
- B both the cork and the beads
- C the cork pieces
Answer
Key: C — the cork pieces
The cork pieces still float, so they rise to the top.
The glass beads still sink, so they drop to the bottom.
Feedback per option
- A The glass beads are still glass, so they still sink.
- B Only the cork floats. The glass beads sink.
- C The cork is still cork in the mixture, so it still floats.
Which property lets a magnet pull steel pins out of a box of plastic buttons?
- A Steel is magnetic, and plastic is not.
- B Steel is shinier than plastic.
- C Steel pins have more mass than buttons.
Answer
Key: A — Steel is magnetic, and plastic is not.
Steel is magnetic, and plastic is not.
That difference lets the magnet lift the pins and leave the buttons.
Feedback per option
- A The magnet pulls on the steel and not on the plastic.
- B A magnet does not pull on shine. It pulls on magnetic materials.
- C A magnet does not pull on mass. It pulls on magnetic materials.
Chloe dissolves salt in a cup of water. She says: "The salt is still salt, so I can get it back by letting the water evaporate." Is Chloe correct?
- A yes
- B no
Answer
Key: A — yes
The salt is still salt, and salt does not evaporate.
The water evaporates and leaves the cup, so the salt is left behind, and Chloe is correct.
Feedback per option
- A Each substance keeps its own properties in a mixture. The water evaporates and the salt does not, so the salt is left in the cup.
- B Dissolving did not destroy the salt. The salt is still salt, and salt does not evaporate, so it is left in the cup when the water goes.
A magnet is held over a can of aluminum pull-tabs and rubber bands. Neither aluminum nor rubber is magnetic. Does the magnet separate the tabs from the bands?
- A yes
- B no
Answer
Key: B — no
Neither aluminum nor rubber is magnetic, so the magnet pulls on neither part.
A property that both parts lack cannot separate them, so the magnet lifts nothing.
Feedback per option
- A The magnet pulls on neither part, so it lifts nothing.
- B A property that both parts lack cannot pull them apart. The magnet lifts nothing.
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
Evenly mixed or not: homogeneous and heterogeneous
MAT-030 · Homogeneous and heterogeneous mixtures — Classify a mixture as homogeneous or heterogeneous based on whether it is uniform throughout.
Script
| Say | Screen |
|---|---|
| A student stirs salt into a glass of water until it disappears. | [a glass; salt stirs in and vanishes] |
| She stirs sand into a second glass of water. | [a second glass; sand sinks to the bottom] |
| Are these two mixtures the same kind of mixture? | [question mark] |
| No, they are mixed in two different ways. | [the two glasses side by side] |
| Zoomed in on the salt water, the salt particles are spread evenly among the water particles. | [sample box: open salt particles spread evenly among filled water particles] |
| Every sip is the same, so the salt water is the same all through. | [three sips marked on the glass; all the same] |
| Zoomed in on the sandy water, the sand particles sit below the water particles. | [sample box: open sand particles along the bottom, filled water particles above] |
| So the sandy water is not the same all through. | [top and bottom of the glass marked; different] |
| A mixture that is the same all the way through is called homogeneous: homo means the same. | [chip: HOMOGENEOUS, EVENLY MIXED] |
| A mixture that is different in different places is called heterogeneous: hetero means different. | [chip: HETEROGENEOUS, NOT EVENLY MIXED] |
| Both are mixtures. | [both glasses labeled MIXTURE, then the two terms beneath] |
| Air is homogeneous, because every breath is the same. | [air box with a tick under EVENLY MIXED?] |
| Trail mix is heterogeneous, because every handful differs. | [bowl of trail mix with a cross under EVENLY MIXED?] |
| Brass is copper and zinc spread evenly, so it is homogeneous. | [brass box: two kinds spread evenly; tick] |
| So, here's what we've seen. A mixture that is the same all the way through is called homogeneous. | [the rule slide: the salt water box; chip HOMOGENEOUS, EVENLY MIXED; nothing else printed] |
| A mixture that is different in different places is called heterogeneous. | [the sandy water box; chip HETEROGENEOUS, NOT EVENLY MIXED] |
| So the salt water is homogeneous, and the sandy water is heterogeneous. | [the two glasses with their terms and plain words] |
| Okay, now your turn. | [the rule slide's images hold; closing screen: bullets — • A mixture that is the same all the way through is called homogeneous. • A mixture that is different in different places is called heterogeneous.] |
“Okay, now your turn.” — the attached question
Salt water is the same all the way through. Which word describes that mixture?
- A homogeneous
- B heterogeneous
Answer
Key: A — homogeneous
Every sip of the salt water is the same.
So the salt water is homogeneous, evenly mixed.
Feedback per option
- A Homo means the same: the same all the way through is homogeneous.
- B Hetero means different. The salt water is the same all the way through.
Quiz after the video — the mastery check, 14 items
A lemon is squeezed into a glass of water. Is the lemon water a mixture or a pure substance?
- A a mixture
- B a pure substance
Answer
Key: A — a mixture
Two or more substances mingled together make a mixture.
So the lemon water is a mixture.
Feedback per option
- A Lemon juice and water are two substances mingled together.
- B A pure substance is one kind of matter only. Lemon juice and water are two.
A mixture that is the same all the way through, evenly mixed, is called…
Typed answer
Answer
Accepted: homogeneous · homogenous
Homo means the same.
A mixture that is different in different places, not evenly mixed, is called…
Typed answer
Answer
Accepted: heterogeneous · heterogenous
Hetero means different.
A student calls a mixture homogeneous. What does she mean?
- A It is the same all the way through.
- B It has settled into two separate layers.
- C It is really a pure substance.
Answer
Key: A — It is the same all the way through.
Homo means the same.
So she means the mixture is evenly mixed.
Feedback per option
- A Homo means the same: the mixture is evenly mixed.
- B Two layers means different in different places: heterogeneous.
- C A homogeneous mixture is still a mixture, with two or more substances in it.
A student calls a mixture heterogeneous. What does she mean?
- A It is the same all the way through.
- B It is different in different places.
- C It is not a mixture at all, just one substance.
Answer
Key: B — It is different in different places.
Hetero means different.
So she means the mixture is not evenly mixed.
Feedback per option
- A The same all the way through is homogeneous. Hetero means different.
- B Hetero means different: the mixture is not evenly mixed.
- C A heterogeneous mixture is still a mixture, with two or more substances in it.
Filled and open circles are two different kinds of particle. Evenly mixed, or not?
- A homogeneous (evenly mixed)
- B heterogeneous (not evenly mixed)
Answer
Key: A — homogeneous (evenly mixed)
The open circles are spread evenly among the filled circles.
The sample is the same all the way through, so it is homogeneous (evenly mixed).
Feedback per option
- A The open circles are spread evenly among the filled ones: the same all the way through.
- B The two kinds are spread evenly through the whole box, not gathered in one place.
Sweetened cold coffee, stirred: every sip tastes the same. Evenly mixed, or not?
- A homogeneous (evenly mixed)
- B heterogeneous (not evenly mixed)
Answer
Key: A — homogeneous (evenly mixed)
So the coffee is the same all the way through.
A mixture that is the same all the way through is homogeneous (evenly mixed).
Feedback per option
- A Every sip the same means the same all the way through.
- B Every sip is the same, so the coffee is not different in different places.
A fruit salad: pieces of apple, melon and grape. Evenly mixed, or not?
- A homogeneous (evenly mixed)
- B heterogeneous (not evenly mixed)
Answer
Key: B — heterogeneous (not evenly mixed)
So the salad is different in different places.
A mixture that is different in different places is heterogeneous (not evenly mixed).
Feedback per option
- A One spoonful is mostly apple, the next mostly melon: different in different places.
- B Different spoonfuls hold different fruit, so the salad is different in different places.
Filled and open circles are two different kinds of particle. Evenly mixed, or not?
- A homogeneous (evenly mixed)
- B heterogeneous (not evenly mixed)
Answer
Key: B — heterogeneous (not evenly mixed)
The open circles gather on the left side, and the filled circles fill the rest.
The sample is different in different places, so it is heterogeneous (not evenly mixed).
Feedback per option
- A The open circles gather on the left side, so the left differs from the right.
- B The open circles gather on the left side: different in different places.
Oil poured onto vinegar: the oil floats in a layer on top. Evenly mixed, or not?
- A homogeneous (evenly mixed)
- B heterogeneous (not evenly mixed)
Answer
Key: B — heterogeneous (not evenly mixed)
So the sample is different in different places.
A mixture that is different in different places is heterogeneous (not evenly mixed).
Feedback per option
- A Oil on top and vinegar below is different in different places.
- B The oil sits in one place and the vinegar in another: different in different places.
A sports drink: every mouthful is the same. Evenly mixed, or not?
- A homogeneous (evenly mixed)
- B heterogeneous (not evenly mixed)
Answer
Key: A — homogeneous (evenly mixed)
So the drink is the same all the way through.
A mixture that is the same all the way through is homogeneous (evenly mixed).
Feedback per option
- A Every mouthful the same means the same all the way through.
- B Every mouthful is the same, so the drink is not different in different places.
Filled and open circles are two different kinds of particle. Evenly mixed, or not?
- A homogeneous (evenly mixed)
- B heterogeneous (not evenly mixed)
Answer
Key: A — homogeneous (evenly mixed)
The open circles are spread evenly among the filled circles.
The sample is the same all the way through, so it is homogeneous (evenly mixed).
Feedback per option
- A The two kinds are spread evenly through the whole box: the same all the way through.
- B The open circles are spread through the whole box, not gathered in one place.
A chocolate chip cookie: chips here and there in the dough. Evenly mixed, or not?
- A homogeneous (evenly mixed)
- B heterogeneous (not evenly mixed)
Answer
Key: B — heterogeneous (not evenly mixed)
So the cookie is different in different places.
A mixture that is different in different places is heterogeneous (not evenly mixed).
Feedback per option
- A One bite has two chips and the next has none: different in different places.
- B Chips here and there means the cookie is different in different places.
Ezra shakes gravel into a jar of water, and the gravel sinks to the bottom. He says: "The gravel and the water are not evenly mixed, so this is not a real mixture." Is Ezra correct?
- A yes
- B no
Answer
Key: B — no
The gravel and the water are two substances in one jar, so the jar holds a mixture.
Gravel below and water above is not evenly mixed, so the mixture is heterogeneous, and Ezra is not correct.
Feedback per option
- A Evenly mixed is not the test for a mixture. Gravel and water are two substances in one jar, so it is a mixture: a heterogeneous one.
- B Gravel and water mingled in one jar are a mixture. Not evenly mixed only means the mixture is heterogeneous.
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
Sort any sample: the decision tree
MAT-032 · Classify any sample as pure substance, homogeneous mixture, or heterogeneous mixture — Follow the classification decision tree to place any described sample into the correct category.
Script
| Say | Screen |
|---|---|
| A student is handed four cups: distilled water, the kind sold for steam irons, salt water, sandy water, and table sugar. | [four cups, each named] |
| She must sort each cup: pure substance, homogeneous mixture, or heterogeneous mixture. | [three empty category boxes: PURE SUBSTANCE, HOMOGENEOUS MIXTURE, HETEROGENEOUS MIXTURE] |
| Which two questions should she ask, and in which order? | [question mark] |
| Question 1 is: is there more than one kind of matter? | [the tree: question 1 box] |
| No means a pure substance; yes means a mixture, so ask question 2. | [arrows: NO → pure substance; YES → question 2] |
| Question 2 is: is the mixture the same all the way through? | [question 2 box] |
| Yes means homogeneous, evenly mixed; no means heterogeneous, not evenly mixed. | [arrows: YES → homogeneous; NO → heterogeneous; particle boxes under each] |
| For the salt water, question 1 is yes: it holds salt and water, so it is a mixture. | [salt water cup moves to question 2] |
| Question 2 is yes, every sip is the same, so it is a homogeneous mixture. | [cup lands in HOMOGENEOUS MIXTURE] |
| For the sandy water, question 1 is yes and question 2 no, so it is a heterogeneous mixture. | [cup lands in HETEROGENEOUS MIXTURE] |
| For the distilled water, question 1 is no, so it is a pure substance. | [cup lands in PURE SUBSTANCE] |
| For the table sugar, question 1 is no, so it is a pure substance too. | [cup lands in PURE SUBSTANCE] |
| So, to sort a sample, ask two questions in order: is there more than one kind of matter? Is it the same all the way through? | [the rule slide: the tree with question 1 then question 2 highlighted; nothing else printed] |
| Okay, now your turn. | [the rule slide's images hold; closing screen: bullets — • Question 1: is there more than one kind of matter? • Question 2: is it the same all the way through?] |
“Okay, now your turn.” — the attached question
For a cup of sandy water, question 1 is yes and question 2 is no. Which category is the sandy water?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: C — a heterogeneous mixture
Question 2 is no, so the mixture is not the same all the way through.
A mixture that is different in different places is heterogeneous.
Feedback per option
- A Question 1 is yes, so the sandy water is a mixture.
- B Question 2 is no: sand below and water above is not the same all the way through.
- C Yes to question 1 and no to question 2 lands on heterogeneous.
Quiz after the video — the mastery check, 13 items
A silver ring: every particle in it is a silver particle. Is the ring a pure substance?
- A yes
- B no
Answer
Key: A — yes
Every particle in the ring is a silver particle.
So the ring is a pure substance.
Feedback per option
- A One kind of particle only, so the ring is a pure substance.
- B Every particle is a silver particle, so the ring holds one kind of matter.
Corn and black beans are stirred together in a pan. Is the corn with beans a pure substance or a mixture?
- A a pure substance
- B a mixture
Answer
Key: B — a mixture
Two or more substances mingled together make a mixture.
So the corn with beans is a mixture.
Feedback per option
- A A pure substance is one kind of matter only. Corn and beans are two.
- B Corn and beans are two substances mingled together.
Chocolate syrup is stirred into milk until every sip tastes the same. Homogeneous or heterogeneous?
- A heterogeneous (not evenly mixed)
- B homogeneous (evenly mixed)
Answer
Key: B — homogeneous (evenly mixed)
So the chocolate milk is the same all the way through.
A mixture that is the same all the way through is homogeneous (evenly mixed).
Feedback per option
- A Every sip is the same, so the milk is not different in different places.
- B Every sip the same means the same all the way through.
A jar of muddy pond water: bits of soil lie at the bottom, and clearer water sits above. Question 1: is there more than one kind of matter in the jar?
- A yes
- B no
Answer
Key: A — yes
Soil and water are two kinds of matter.
So the answer to question 1 is yes: the pond water is a mixture.
Feedback per option
- A Soil and water are two kinds of matter.
- B The jar holds soil and water, which are two kinds of matter.
The muddy pond water again: soil at the bottom, clearer water above. Question 2: is it the same all the way through?
- A yes
- B no
Answer
Key: B — no
The bottom and the top hold different things.
So the answer to question 2 is no: the pond water is not the same all the way through.
Feedback per option
- A Soil at the bottom and clearer water above are different places holding different things.
- B The bottom of the jar holds soil and the top holds clearer water, so the jar is different in different places.
So which category is the muddy pond water: soil at the bottom, clearer water above?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: C — a heterogeneous mixture
Question 2: soil below and clearer water above, so no: the mixture is not the same all the way through.
A mixture that is different in different places is heterogeneous.
Feedback per option
- A Soil and water are two kinds of matter, so question 1 is yes: a mixture, not a pure substance.
- B Soil below and clearer water above is not the same all the way through, so question 2 is no: not homogeneous.
- C A mixture that is not the same all the way through is heterogeneous.
Filled and open circles are two different kinds of particle. Which category is this sample?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: A — a pure substance
Every circle is filled, so there is one kind only: no.
So the sample is a pure substance, and question 2 is not needed.
Feedback per option
- A Every circle is filled: one kind of particle, so question 1 is no.
- B Evenly spread does not make a mixture. Every circle is filled, so there is one kind of particle: not a mixture at all.
- C A heterogeneous mixture needs two kinds of particle, unevenly spread. Every circle is filled, so there is one kind only.
Sweet tea: honey dissolved in tea, and every sip tastes the same. Which category?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: B — a homogeneous mixture
Question 2: every sip is the same, so yes.
A mixture that is the same all the way through is homogeneous.
Feedback per option
- A Honey and tea are two kinds of matter, so question 1 is yes.
- B Question 1 yes, question 2 yes: the same all the way through.
- C Every sip is the same, so question 2 is yes, not no.
A box of baking soda: every particle in it is the same kind. Which category?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: A — a pure substance
Every particle is the same kind, so no.
So the baking soda is a pure substance, and question 2 is not needed.
Feedback per option
- A One kind of particle only, so question 1 is no.
- B A homogeneous mixture needs two kinds of matter evenly mixed. Baking soda has one kind of particle only, so it is not a mixture.
- C A heterogeneous mixture needs two kinds of matter unevenly mixed. Baking soda has one kind of particle only, so it is not a mixture.
Noodles with peas stirred in, peas here and there. Which category?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: C — a heterogeneous mixture
Question 2: peas here and there, so the dish is not the same all the way through: no.
A mixture that is different in different places is heterogeneous.
Feedback per option
- A Noodles and peas are two kinds of matter, so question 1 is yes.
- B Peas here and there means different in different places, so question 2 is no.
- C Question 1 yes, question 2 no: not the same all the way through.
Filled and open circles are two different kinds of particle. Which category is this sample?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: C — a heterogeneous mixture
Question 2: the open circles gather on the right side, so the box is not the same all the way through: no.
A mixture that is different in different places is heterogeneous.
Feedback per option
- A Filled and open circles are two kinds of particle, so question 1 is yes.
- B The open circles gather on the right side, so question 2 is no.
- C Question 1 yes, question 2 no: the open circles gather on the right side.
Clear apple juice: several substances mingled, and every sip the same. Which category?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: B — a homogeneous mixture
Question 2: every sip is the same, so yes.
A mixture that is the same all the way through is homogeneous.
Feedback per option
- A Several substances mingled means more than one kind of matter, so question 1 is yes.
- B Question 1 yes, question 2 yes: every sip is the same.
- C Every sip is the same, so question 2 is yes, not no.
When sorting any sample, which question do you ask first?
- A Is there more than one kind of matter?
- B Is it the same all the way through?
- C Is it a solid, a liquid or a gas at room temperature?
Answer
Key: A — Is there more than one kind of matter?
A no ends the sort at pure substance.
A yes means a mixture, and only then is question 2 asked.
Feedback per option
- A Question 1 sorts pure substances from mixtures. Only mixtures go on to question 2.
- B That is question 2, asked only once the sample is known to be a mixture.
- C A pure substance can be a solid, a liquid or a gas, so the state is not the test.
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: Pure substances and mixtures
Script, part 1 (100 words)
| Say | Screen |
|---|---|
| Here is everything we found out about pure substances and mixtures. | [a still: the two glasses, the heap and the tray with the magnet] |
| All matter is made of particles that are far too small to see. | [a zoom circle] |
| A sample that contains only one kind of matter is called a pure substance. | [chip: PURE SUBSTANCE; box of filled circles only] |
| Zoom in, and every particle is the same kind. | [the box holds] |
| But a sample that contains two or more substances mingled together is called a mixture. | [chip: MIXTURE; box of filled and open circles] |
| Each substance keeps its own particles, so stirring does not turn two substances into one. | [the box holds; the two kinds stay two kinds] |
| And in a mixture each substance keeps its own properties, so the parts of a mixture can be separated. | [chip: EACH PART KEEPS ITS OWN PROPERTIES; the magnet with its filings above the sand] |
| Okay, now your turn. | [the still holds] |
“Okay, now your turn.” — the check question between the parts
A sample holds water particles and salt particles mingled together. Is it a pure substance or a mixture?
- A a pure substance
- B a mixture
Answer
Key: B — a mixture
Water particles and salt particles are two substances.
So the sample is a mixture.
Feedback per option
- A A pure substance holds only one kind of matter.
- B Two substances mingled together make a mixture.
Script, part 2 (115 words)
| Say | Screen |
|---|---|
| Here is everything we found out about sorting mixtures and samples. | [a still: the salt water box and the sandy water box] |
| A mixture that is the same all the way through is called homogeneous, evenly mixed. | [chip: HOMOGENEOUS, EVENLY MIXED] |
| A mixture that is different in different places is called heterogeneous, not evenly mixed. | [chip: HETEROGENEOUS, NOT EVENLY MIXED] |
| Both are mixtures; the words only say how evenly each is mixed. | [both boxes labeled MIXTURE] |
| To sort a sample, ask two questions in order: is there more than one kind of matter? Is it the same all the way through? | [the decision tree] |
| No to the first question means a pure substance; yes means a mixture, so ask the second question. | [arrows on the tree] |
| Yes to the second question means the mixture is homogeneous; no means the mixture is heterogeneous. | [the three category boxes] |
| Okay, now your turn. | [the tree holds] |
“Okay, now your turn.” — the two questions after part 2
Every handful of trail mix is different. Which word describes trail mix?
- A homogeneous
- B heterogeneous
Answer
Key: B — heterogeneous
Every handful of trail mix differs.
So trail mix is heterogeneous.
Feedback per option
- A Homo means the same. Every handful of trail mix differs.
- B Hetero means different: a mixture that is different in different places is heterogeneous.
A cup holds table sugar, and every particle in it is a sugar particle. Which category is the table sugar?
- A a pure substance
- B a homogeneous mixture
- C a heterogeneous mixture
Answer
Key: A — a pure substance
So table sugar is a pure substance, and question 2 is not needed.
Feedback per option
- A Every particle in table sugar is a sugar particle: one kind of matter only.
- B Question 1 is no, so the sugar is not a mixture of any kind.
- C Question 1 is no, so the sugar is not a mixture of any kind.
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)
- All matter is made of particles that are far too small to see.
- A sample that contains only one kind of matter is called a pure substance.
- A sample that contains two or more substances mingled together is called a mixture.
- In a mixture each substance keeps its own properties, so the parts of a mixture can be separated.
- A mixture that is the same all the way through is called homogeneous. A mixture that is different in different places is called heterogeneous.
- To sort a sample, ask two questions in order: is there more than one kind of matter? Is it the same all the way through?
Scripts, questions and quizzes are read from the course content as it stands today; the student site for this topic is here.