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Sink or Float? Testing Objects in Water

Students predict and test whether objects sink or float, discovering that it isn’t just about size — it’s about how heavy something is for its size, a first taste of properties of matter.

Grade 2Matter40 minutes1 class period5E ModelExplicit teaching4 StandardsCommon Core
Start the Lesson
Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Predict if an object will sink or float.
  • ✓Test objects in water.
  • ✓Notice that heaviness-for-size matters.
  • ✓Sort objects by whether they float.
Essential Question

A tiny coin sinks, but a big log floats. If it’s not just about size, what makes something sink or float?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Water Tank · Interactive

The Water Tank

Project this and tap each object to drop it in the tank. Have students predict first, then watch whether it sinks or floats — and talk about why.

🌊 Drop an object in — will it sink or float?Try it

Tap an object to drop it in the water — will it sink or float?

The Lesson · 5E Model

40 minutes, five moves

Tap any phase to open the teacher moves and student actions.

1

Engage — Big Log, Tiny Coin

5 min

A big log floats but a little coin sinks — how?

👩‍🏫 Teacher Moves

  • Show a big floater and a small sinker.
  • Ask why size isn’t the answer.
  • Set the goal: sink or float.

🎒 Student Actions

  • Compare the two.
  • Notice size isn’t it.
  • Predict the reason.
2

Explore — Test in the Tank

10 min

Students investigate.

👩‍🏫 Teacher Moves

  • Send students to the Water Tank.
  • Have them predict, then test.
  • Record sink or float.

🎒 Student Actions

  • Predict first.
  • Drop and watch.
  • Record the result.
3

Explain — Heavy for Its Size

10 min

Teacher explains.

👩‍🏫 Teacher Moves

  • Explain heaviness-for-size (density, simply).
  • Light-for-size floats; heavy-for-size sinks.
  • Note trapped air helps floating.

🎒 Student Actions

  • Explain the idea.
  • Sort by float/sink.
  • Note trapped air.
4

Elaborate — Test Real Objects

10 min

Apply.

👩‍🏫 Teacher Moves

  • Test classroom objects in a tub.
  • Predict before each test.
  • Look for patterns.

🎒 Student Actions

  • Predict each object.
  • Test it.
  • Find a pattern.
5

Evaluate — Exit Ticket

5 min

Three quick checks.

👩‍🏫 Teacher Moves

  • Hand out the exit ticket.
  • Look for prediction + reason.
  • Collect as formative data.

🎒 Student Actions

  • Predict an object.
  • Give a reason.
  • Explain a result.
Standards Alignment

Built to the standards you report on

Aligned to Next Generation Science Standards and Common Core literacy. State-standard crosswalks available on request.

NGSS
2-PS1-1

Plan and conduct an investigation to describe and classify materials by their observable properties.

NGSS
2-PS1-2

Test materials and analyze data to determine which are best suited for a purpose.

NGSS
K-2-ETS1-1

Ask questions and make observations about a situation people want to change.

CCSS
RI.2.3

Describe the connection between a series of steps in a text.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Predict with thumbs up/down.
  • Sentence frame: “I think the ___ will ___.”
  • Test with real objects and water.

Support & Access

IEP / 504
  • Predict with two picture choices.
  • Test one object at a time.
  • Focus on float vs. sink only.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Make a sinking object float (a boat shape).
  • Sort objects by material.
  • Explain why boats float.
Materials

What to gather

  • 📽️Projector / board
  • 📓Science notebooks
  • 💻The Water Tank
  • 🪣A tub of water
  • 🪨Objects to test
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

sinkto go down under the waterfloatto rest on top of the waterpredictto say what will happentestto try it and seematerialwhat something is made ofheavyhaving a lot of weightpropertya trait of an objectobserveto watch closely
Evaluate

Exit Ticket

Preview the three formative checks. Tap “Sample answer” to see what mastery looks like — hide them before you print for students.

QUESTION 1
Does a cork sink or float?
Float — it is very light for its size.
QUESTION 2
Does a metal coin sink or float?
Sink — it is heavy (dense) for its size.
QUESTION 3
Is it just the SIZE of an object that decides if it floats?
No — it is how heavy the object is for its size (and trapped air can help it float).

Going deeper? Build a boat.

Challenge students to shape a piece of foil so it floats and holds pennies — turning a “sinking” metal into a floating boat. A printable boat-challenge sheet is in the Science library.

Study · Flashcards

Study the key terms

Tap a card to flip it, then rate whether you knew it. Built from this lesson’s vocabulary.

🃏 Sink or FloatFlip
Card 1
Term
Tap to flip →
Meaning
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Nice work!

Practice · Quiz

Check your understanding

A quick self-check with instant feedback, drawn from this lesson’s key terms.

📝 Sink or FloatQuiz
Score: 0
1 / 6
Question 1
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Nice work!

Practice · Worksheet

Printable worksheet

A print-and-go review sheet with a built-in answer key. Tap “Show answer key” to reveal answers, or print the clean version for students.

🖨️ Sink or FloatPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: float, heavy, material, observe, predict, property, sink, test
  1. to go down under the water
  2. a trait of an object
  3. what something is made of
  4. to say what will happen
  5. to try it and see
  6. to watch closely
  7. having a lot of weight
  8. to rest on top of the water

Part B · Show what you learned

  1. Does a cork sink or float?
  2. Does a metal coin sink or float?
  3. Is it just the SIZE of an object that decides if it floats?
Answer key — Part A: 1) sink · 2) property · 3) material · 4) predict · 5) test · 6) observe · 7) heavy · 8) float
Part B: 1) Float — it is very light for its size. 2) Sink — it is heavy (dense) for its size. 3) No — it is how heavy the object is for its size (and trapped air can help it float).