🚢 🧲 🧪 ⚓
Lesson

Physical Properties of Matter

A 100,000-ton steel ship floats across the ocean, but a steel coin dropped overboard sinks instantly. Same material, opposite results. Why?

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Driving Question
How can we use properties like density and buoyancy to predict what matter will do, and to identify what a material is?
🔬 Learning Science Focus 🔍 Phenomenon First 🏷️ Label After Learning 🪜 Stepwise Scaffolds ✏️ Generation Effect ✅ Retrieval Practice
Learning Goals

What You'll Be Able to Do

By the end of this lesson, you will be able to:

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Explain density as how much matter is packed in a space, and use it to predict whether an object will sink or float.
6.MS-PS1-7(MA)
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Measure volume two ways: length x width x height for regular objects, and the water displacement method for irregular objects.
6.MS-PS1-7(MA)
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Describe buoyancy as the upward force on objects in water, and explain why an object floats when it pushes aside enough water.
6.MS-PS1-7(MA)
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Identify physical properties of matter - like hardness, conductivity, magnetism, and melting point - and match them to real materials.
6.MS-PS1-8(MA)
📚 Instructional Design
Why this section exists
  • Names the four outcomes up front: density, volume, buoyancy, and identifying physical properties.
  • Anchors every goal to 6.MS-PS1-7 and 6.MS-PS1-8 so the lesson stays in scope.
Cognitive science
  • Advance organizer: students see the target before the content.
  • Goal setting primes attention for the measure-then-identify arc.
Bloom's / DOK
  • Understand to Analyze
  • DOK 2 to 3 (goals ask students to explain density and predict floating from evidence)
Accessibility considerations
  • Four icon-led cards, large targets, low text load.
  • Plain "be able to" wording.
  • Standard codes shown but not required reading.
Key Vocabulary

Words You'll Meet

Choose a card to see what each word means.

📚 Instructional Design
Why this section exists
  • Front-loads the terms students will meet so reading the lesson is not slowed by new words.
  • Gives a stable reference students can return to during the labs.
Cognitive science
  • Click-to-reveal adds a small retrieval cue before the definition shows.
  • One card open at a time reduces split attention.
Bloom's / DOK
  • Remember to Understand
  • DOK 1 (recall and recognize term meanings)
Accessibility considerations
  • Color-coded cards aid scanning without relying on color alone.
  • Definitions stay short and concrete.
  • Large tap targets, no hover dependency.
Engage · Mystery

One Harbor. Three Puzzles.

Picture Boston Harbor on a summer day. Look closely at what's floating and what's sinking, and things stop making sense.

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The Steel Giant
A container ship made of thousands of tons of solid steel glides across the water without sinking an inch.
Steel is heavy. Why doesn't the ship sink?
Click to look closer
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The Tiny Coin
A sailor drops a small steel coin over the railing. It weighs almost nothing, yet it sinks straight to the bottom.
The coin is a million times lighter than the ship. Why does IT sink?
Click to look closer
🧊
The Floating Ice
Chunks of ice bob at the surface. But ice is just solid water - it's made of exactly the same stuff it's floating in.
How can water float on water?
Click to look closer
💡 One clue: whether something sinks or floats has nothing to do with how heavy it is. A tiny coin sinks while a giant ship floats.
🤔 If weight isn't the answer, what is? What do the floaters have in common that the sinkers don't?
The question: Ships, coins, ice cubes, and life jackets all obey the same hidden rule. This lesson is about discovering that rule - and the measurable properties behind it.
📚 Instructional Design
Why this section exists
  • Opens a discrepant event: a heavy ship floats while a light coin sinks.
  • Confronts the misconception that heavier objects always sink.
Cognitive science
  • Curiosity gap: the puzzle creates a need-to-know before instruction.
  • Cognitive conflict makes the upcoming density rule more memorable.
Bloom's / DOK
  • Understand to Apply
  • DOK 2 (students notice a pattern and form a question, not yet justify)
Accessibility considerations
  • Dual coding: icon plus short text on each puzzle card.
  • Click-to-reveal keeps each card low-load until chosen.
  • Concrete, everyday objects lower the entry barrier.
Explore · The Hidden Rule

What Is Density?

The hidden rule starts with a question: how much matter is packed into a space? Three blocks below are exactly the same size. The dots show the particles of matter inside each one.

Same size · different packing · Which block has the highest density?
The key idea

Density tells us how much matter is packed in a space. Objects with high density usually sink. Objects with low density usually float. That's the hidden rule from the harbor: floaters are less dense than water, sinkers are more dense.

🪙 The coin sinks because solid steel is tightly packed - much denser than water.
🚢 The ship floats because it isn't solid steel. Its hull is full of air, so the ship as a whole is less dense than water.
But density compares matter to space. To work with it, we need a way to measure the space part - the volume.

Easy for a box. Trickier for a rock. Let's measure both.
📚 Instructional Design
Why this section exists
  • Builds the core idea: density is how much matter is packed into a space.
  • Confronts the "density just means heavy" misconception with same-size blocks.
Cognitive science
  • Model-based reasoning: particle dots make an invisible idea visible.
  • Controlling for size isolates the variable students should attend to.
Bloom's / DOK
  • Understand to Analyze
  • DOK 2 (compare packing across equal-size blocks to explain density)
Accessibility considerations
  • Dual coding: particle diagram paired with plain-language definition.
  • Interactive feedback confirms reasoning step by step.
  • Bridge callout signals what comes next.
Explore · Measuring Space

Calculating Volume

Volume is how much space an object takes up. For regular objects - shapes with straight edges, like boxes - the formula is simple: length x width x height.

📦 Volume Calculator
Try it yourself. Type any length, width, and height in centimeters and watch the volume update. Start with 4 x 3 x 2.
x
x
Volume24 cm³
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Think about it: Now you pick up a bumpy rock. It has no straight edges to measure - no length, width, or height. How could you find ITS volume? Make a prediction.
The trick scientists use

For irregular objects, we use the water displacement method. The rock pushes water out of its way, and the water has nowhere to go but up. The rise in the water level equals the rock's volume exactly. (Mass and volume are NOT the same - a scale measures matter, not space.)

🧪 The Water Displacement Lab
Follow the same four steps a scientist follows, then read the cylinder yourself.
1Record the starting water level.
2Gently drop the object into the graduated cylinder.
3Record the new water level.
4The difference between the levels is the volume.
0 20 40 60 80 100
Starting level
40 mL
New level
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The water rose from 40 mL to 65 mL. What is the rock's volume?
You can now measure how much space anything takes up - box or boulder. Notice something, though: the rock pushed the water aside, and the water pushed back.

That push has a name, and it's the last piece of the ship mystery.
📚 Instructional Design
Why this section exists
  • Gives students two concrete tools to measure volume: a formula and displacement.
  • Supplies the "space" half of density so the rule becomes usable.
Cognitive science
  • Measurement reasoning: students manipulate inputs and read the result.
  • Worked-then-applied: regular shape first, irregular rock second.
Bloom's / DOK
  • Understand to Apply
  • DOK 2 (apply a method and interpret a measured volume)
Accessibility considerations
  • Numeric inputs use inputmode numeric for mobile keyboards.
  • Animated displacement gives a visual model alongside numbers.
  • Units shown with every result to anchor meaning.
Explore · The Upward Push

What Is Buoyancy?

When an object enters water, it shoves some water out of the way - you just saw that in the displacement lab. The water pushes back with an upward force.

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Think about it: The steel ship pushes aside a HUGE amount of water. The steel coin pushes aside barely any. Which one do you think gets a bigger upward push from the water?
Key idea

Buoyancy is the upward force that makes an object float. Here's the rule: an object floats when the water it pushes aside weighs as much or more than the object itself. The ship's wide, hollow hull pushes aside thousands of tons of water - more than the ship weighs - so the water holds it up. The coin pushes aside only a coin-sized drop of water, far less than the coin weighs, so down it goes.

🦺 Life jackets work the same way: they add lots of space (volume) but almost no weight, so you push aside more water than you weigh.
🧊 Ice floats because frozen water particles lock into a spread-out pattern - ice is slightly less dense than liquid water.

Making Connections

ConceptWhat It Explains
DensityWhy materials sink or float
Water DisplacementHow we measure the volume of odd shapes
BuoyancyWhy objects rise or sink in water
Density, volume, and buoyancy are all things you can observe or measure about a material without changing what it is. It turns out there's a whole family of properties like that.

Time to meet the rest of the family.
📚 Instructional Design
Why this section exists
  • Resolves the ship puzzle: floating depends on the water an object pushes aside.
  • Connects density and displacement into a single cause-and-effect story.
Cognitive science
  • Cause-and-effect reasoning links force, displaced water, and floating.
  • Callback to the harbor closes the curiosity gap opened in Engage.
Bloom's / DOK
  • Understand to Analyze
  • DOK 2 to 3 (explain why an object floats using displaced-water evidence)
Accessibility considerations
  • Summary table consolidates the three linked ideas.
  • Prediction prompt invites a guess before the explanation.
  • Short sentences keep the force idea manageable.
Explore · The Whole Family

Physical Properties of Matter

A physical property is a characteristic we can observe or measure without changing what the material is. Bending a paperclip doesn't turn it into a different metal. Melting ice doesn't turn it into a different substance. Here are eight properties scientists use to identify and choose materials.

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Flexibility
The ability to bend without breaking.
🐍 Garden hose
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Ductility
The ability to be stretched into a thin wire.
⚡ Copper wiring
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Hardness
The resistance to scratching or denting.
💍 Diamond drill tip
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Melting Point
The temperature where a solid becomes a liquid.
🧊 Ice melts at 0°C
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Thermal Conductivity
How easily heat moves through a material.
🍳 Metal pan heats fast
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Electrical Conductivity
How easily electric current flows through a material.
🔌 Wires are metal
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Magnetism
The ability to attract certain metals, such as iron or steel.
🚪 Fridge magnets
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Malleability
The ability to be reshaped, bent, or flattened without breaking.
🥫 Aluminum foil
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Watch out for the look-alikes: ductility is stretching into a wire, malleability is flattening into a sheet, and flexibility is bending and springing back. Three different superpowers.
🔧 The Engineer's Property Match
You're the engineer. For each design problem, pick the ONE physical property that matters most. Get all five to earn your badge.
⚡ Loading...
🏆 Five for five! You just thought like a materials engineer - choosing materials by their physical properties is exactly how real products get designed.
📚 Instructional Design
Why this section exists
  • Generalizes from density to the full set of physical properties used to identify materials.
  • Reinforces that physical properties do not change what the substance is.
Cognitive science
  • Classification practice: students match a design problem to the property that matters.
  • Spaced retrieval across five scenarios strengthens the property-to-use link.
Bloom's / DOK
  • Understand to Analyze
  • DOK 2 (sort materials by property and explain how a property fits a use)
Accessibility considerations
  • Property cards use icon plus label for dual coding.
  • Live-region feedback announces results for screen readers.
  • Progress dots show how many scenarios remain.
Quick Recall

Brain Check

Two quick questions before we put it all together. These are not graded. Pulling answers from memory now will help them stick.

Quick Recall · 1 of 2
A quick brain check. Not graded.
A solid rubber ball and a hollow rubber ball are the same size. You drop both in a pool. The solid one sinks; the hollow one floats. Why?
Quick Recall · 2 of 2
One more brain check. Not graded.
A junkyard uses a giant electromagnet to lift steel out of a pile of mixed scrap, leaving the aluminum and plastic behind. Which physical property makes this separation possible?
📚 Instructional Design
Why this section exists
  • Low-stakes retrieval check before the wrap-up and quiz.
  • Surfaces shaky understanding while there is still time to reread.
Cognitive science
  • Retrieval practice: recalling now strengthens later recall.
  • Immediate feedback corrects errors before they harden.
Bloom's / DOK
  • Remember to Apply
  • DOK 2 (apply a property to a sink-or-float and a sorting scenario)
Accessibility considerations
  • "Not graded" wording lowers anxiety.
  • Live-region feedback and a Try Again path support second attempts.
  • Labels tied to questions for screen readers.
Explain · Wrap-Up

Back to the Harbor

You started this lesson with a floating steel giant, a sinking coin, and ice bobbing on its own liquid. Now you can explain all three.

The Answer
Sinking and floating are about density, not weight.
The ship is mostly air inside its hull, so as a whole it's less dense than water. The coin is solid steel - tightly packed matter, denser than water. Ice particles lock into a spread-out pattern, making ice less dense than liquid water.
The Tools
Three ideas work together to explain it.
Each concept answers its own question:
Density · sink or float? Volume · how much space? Buoyancy · how big a push?
The Bigger Picture
Density is one of many physical properties.
Hardness, melting point, conductivity, magnetism, malleability - all are physical properties: characteristics you can observe or measure without changing what the material is. Scientists use them to identify materials, and engineers use them to choose materials.

Everything in One Place

The words to know and the goals you worked toward, gathered in one spot.

TermStudent-Friendly Definition
DensityHow much matter is packed in a space. High density usually sinks; low density usually floats.
VolumeHow much space an object takes up. For regular objects: length x width x height.
Water displacementA way to measure the volume of irregular objects: the difference between the water levels before and after the object goes in.
BuoyancyThe upward force that makes an object float. An object floats when the water it pushes aside weighs as much or more than the object itself.
Physical propertyA characteristic we can observe or measure without changing what the material is.
HardnessResistance to scratching or denting.
Melting pointThe temperature where a solid becomes a liquid.
ConductivityHow easily heat (thermal) or electric current (electrical) moves through a material.
MagnetismThe ability to attract certain metals, such as iron or steel.
MalleabilityThe ability to be reshaped, bent, or flattened without breaking.
Learning GoalsHow You Showed It
Explain density and use it to predict sinking and floating (6.MS-PS1-7). You compared particle packing in three same-size blocks and explained why the ship floats while the coin sinks.
Measure volume for regular and irregular objects (6.MS-PS1-7). You calculated length x width x height in the volume calculator and read a graduated cylinder in the water displacement lab.
Describe buoyancy and explain why objects float or sink. You predicted which object gets the bigger upward push and explained floating using the weight of the water pushed aside.
Identify physical properties and match them to materials (6.MS-PS1-8). You matched five engineering problems to the right property in the Property Match challenge.
Essential question: How can we predict what matter will do and identify what a material is? If you can answer that with the words density, volume, buoyancy, and physical property, you own this lesson.
📚 Instructional Design
Why this section exists
  • Returns to the harbor puzzles so students explain all three with the new vocabulary.
  • Ties each learning goal back to the evidence students produced.
Cognitive science
  • Elaboration: students connect density, volume, buoyancy, and properties into one explanation.
  • Closing the opening loop aids consolidation and transfer.
Bloom's / DOK
  • Understand to Analyze
  • DOK 2 to 3 (justify each outcome using the linked concepts)
Accessibility considerations
  • Goal-to-evidence table organizes the recap for easy scanning.
  • Essential question restates the target in one sentence.
  • Key terms bolded as memory anchors.
Evaluate · Quiz

Check Your Understanding

Ten questions covering everything you discovered, including a cylinder for you to read. Answer every question, then submit.

Your score will not be sent Your score will be sent to your teacher
0 / 10 selected
🧠 Show Your Thinking

Scientists don't just know the answer. They explain their thinking.

Write your own explanation first. Then submit your work to compare your thinking with a model answer.

In one sentence, explain what a physical property is, and how a scientist could use physical properties to identify an unknown material without changing what it is.

One strong way to say it A physical property is a characteristic you can observe or measure - like density, magnetism, hardness, melting point, or conductivity - without changing what the material is, so a scientist can identify an unknown material by measuring its combination of properties and matching that fingerprint to a known substance. If your sentence says physical properties can be measured without changing the material and used to identify it, you have it.

🔍 The Mystery You Came In With You started this lesson with one question: "Why does a giant steel ship float while a tiny steel coin sinks?" If you can explain it with density, volume, and buoyancy, you've solved the mystery.
📚 Instructional Design
Why this section exists
  • Ten-question check mixing recall and applied reasoning across the lesson.
  • Practice mode self-checks; classroom mode reports to the teacher.
Cognitive science
  • Graded retrieval consolidates learning and reveals gaps.
  • Answer explanations turn each item into a feedback moment.
Bloom's / DOK
  • Understand to Apply
  • DOK 1 to 2 (define properties, then apply them to sink-float and sorting cases)
Accessibility considerations
  • Submit stays disabled until every item is answered.
  • Try Again allows a full retake in practice mode.
  • Answer positions and lengths varied to avoid guessing cues.
Go Further

More Learning

You explored the physical properties scientists use to describe matter. Take that observing eye off the screen and put it to work with a hands-on challenge at home.

🔎
Extension
Mystery Material Challenge
Find five objects at home and predict whether each will sink or float, then test them in a bowl of water. Next, design a "mystery material" card: list four physical properties of a household object and see if a partner can guess what it is.
📚 Instructional Design
Why this section exists
  • Extends physical properties into hands-on home tests students can run themselves.
  • Offers transfer beyond the harbor context students started with.
Cognitive science
  • Predict-then-test builds expectation before evidence.
  • Choice and real objects support motivation and transfer.
Bloom's / DOK
  • Apply to Analyze
  • DOK 2 to 3 (predict sink-or-float, then justify a material from several properties)
Accessibility considerations
  • Optional, low-cost materials keep the challenge open to all.
  • Icon-led extension card aids scanning.
  • Optional and self-paced, with no penalty for skipping.
Connections

Connections

These lessons build on what you just learned about physical properties.

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Lesson
Measuring Matter
Density was one of the properties you just explored. Turn it into a number you can calculate from mass and volume, with real units.
Explore
⚛️
Extension
The Hidden World of Matter
Properties like color, hardness, and melting point come from what matter is made of. Want to look ahead? Zoom in and meet the atoms and molecules behind them.
Explore