Little Scientists: Sink or Float?

Materials Needed

• A bowl, tub, or sink filled halfway with water
• A towel for spills
• Several safe objects, such as a plastic spoon, toy block, ball, leaf, rock, sponge, cup, and small toy
• Two containers or paper plates labeled “Sink” and “Float”
• Paper and crayons
• Optional: a simple recording chart

Learning Objectives

By the end of the lesson, the child will be able to:

• Use the words sink and float.
• Make a guess about what an object will do in water.
• Test objects safely and observe what happens.
• Sort objects into sink and float groups.
• Share one thing learned using words, drawings, or gestures.

Success Criteria

I can:

• Say, “I think it will sink,” or, “I think it will float.”
• Place an object gently in the water.
• Tell whether the object sank or floated.
• Sort objects into the correct group.

Introduction: Hook and Objectives

Time: 5 minutes

Show the child a rock and a plastic ball.

Say: “I have a rock and a ball. What do you think will happen if we put them in water? Will they go down or stay on top?”

Explain:

• “When something goes down in water, we say it sinks.”
• “When something stays on top of the water, we say it floats.”

Tell the child: “Today we will make guesses, test objects, and find out what sinks and what floats.”

Body of the Lesson

Part 1: I Do—Teacher or Adult Demonstration

Time: 5 minutes

1. Hold up one object, such as a rock.
2. Say: “I am making a guess. I think the rock will sink.”
3. Place the rock gently in the water.
4. Say: “The rock went down. It sank.”
5. Show a plastic ball and say: “I think the ball will float.”
6. Place the ball gently in the water and say: “The ball stayed on top. It floated.”

Quick check: Ask, “Which word means going down—sink or float?” Let the child answer, point, or show a thumbs-down.

Part 2: We Do—Make Predictions Together

Time: 10 minutes

Place the objects where the child can see them. Test one object at a time.

1. Hold up an object.
2. Ask, “What do you think? Will it sink or float?”
3. Invite the child to place the object gently in the water.
4. Watch carefully together.
5. Say the result: “The sponge floated,” or, “The rock sank.”
6. Place the object on the matching “Sink” or “Float” plate.

Use simple questions:

• “What happened?”
• “Did it go down?”
• “Did it stay on top?”
• “Was your guess right?”

Think and talk: Ask the child to choose one object and explain why they think it will sink or float. Accept all reasonable guesses.

Part 3: You Do—The Sink-or-Float Challenge

Time: 10 minutes

Invite the child to lead the investigation.

1. The child chooses an object.
2. The child makes a guess by saying, pointing to, or drawing “sink” or “float.”
3. The child places the object gently in the water.
4. The child tells what happened.
5. The child sorts the object into the correct group.

Use the sentence frames:

• “I think the _____ will sink.”
• “I think the _____ will float.”
• “The _____ sank.”
• “The _____ floated.”

Give specific feedback:

• “You made a guess before testing.”
• “You watched carefully.”
• “You used the word ‘float’ correctly.”

Part 4: Hands-On Choice Activity

Time: 10 minutes

Let the child choose one activity:

Choice A: Draw the Results

The child draws one object that sank and one object that floated.

Choice B: Make a Prediction Chart

Draw two columns labeled “My Guess” and “What Happened.” Use simple pictures or check marks.

Choice C: Build a Floating Boat

Give the child a plastic cup, foil, or a sponge. Ask: “Can you make something that floats?” Test the creation in water.

Choice D: Movement Game

Say the name of an object. The child crouches down like a sinking object or reaches up like a floating object.

Real-World Connection

Say: “Boats float on water. Some things, like rocks, sink. We can use sink and float words when we play in the bath, visit a pool, or see a boat.”

Formative Assessment

During the lesson, observe whether the child can:

• Use or recognize the words sink and float.
• Make a prediction before testing.
• Place an object safely in the water.
• Identify what happened.
• Sort objects into the correct group.

Quick assessment questions:

• “What does sink mean?”
• “What does float mean?”
• “What did the rock do?”
• “Which object surprised you?”

Summative Assessment: Show What You Know

Place two or three new safe objects near the water. Ask the child to:

1. Choose one object.
2. Predict whether it will sink or float.
3. Test it safely.
4. Tell or show what happened.

The child demonstrates success by correctly using or showing the meaning of sink and float for at least two objects.

Differentiation and Support

For a Child Who Needs More Support

• Use only two objects at first: one that sinks and one that floats.
• Use gestures: point down for sink and point up for float.
• Offer choices: “Will it sink or float?”
• Use picture labels instead of written words.
• Repeat the same sentence: “It went down. It sank.”

For a Child Ready for More Challenge

• Ask the child to explain why they made a prediction.
• Test objects made from different materials.
• Compare a full cup and an empty cup.
• Challenge the child to build a boat that holds small toys.
• Ask, “Can you change a sinking object so it floats?”

Safety Notes

• An adult should supervise all water play.
• Use only large objects that cannot be swallowed.
• Keep the water container shallow.
• Wipe up spills right away.

Conclusion: Closure and Recap

Time: 5 minutes

Gather the child and look at the two sorted groups.

Say:

• “Today we tested objects in water.”
• “Objects that go down sink.”
• “Objects that stay on top float.”
• “Scientists make guesses, test ideas, and watch what happens.”

Ask the child to complete one or more sentences:

• “I learned that _____.”
• “The _____ sank.”
• “The _____ floated.”
• “My favorite test was _____.”

Finish with a cheerful chant:

“Down, down, sink! Stay on top, float! We tested and learned—great scientist work!”