Sink and Float Adventure!

In this activity, children will predict and test whether household objects will sink or float in water! 

Learning Objectives

  • Science Content Knowledge: Build basic knowledge about object properties that affect density

  • Science Process Skills: observation, classification, experimentation, and communication

  • Developmental Skills: fine motor control

Materials:

water table close up.jpeg

  • Tub with saltwater

  • Rubber Duck

  • Egg

  • Apple

  • Crayon

  • Sponge

  • Pencil

  • Bottle Cap

  • Empty Water Bottle

Set-Up

  • Collect objects from the materials list

  • Fill one tub with water

  • Print and cut out 2 copies of the Object Icons

  • Print Sink or Float Experiment Worksheets

Activity Instructions

Step 1: Investigate Materials

How dense an object is determines whether it will sink or float. Make observations about and compare the objects. While

  1. How BIG is the object?

  2. How HEAVY is the object?

  3. Is the object POROUS?

Step 2: Classify! Use your observations to make a hypothesis about whether an object will sink or float and then sort them into two groups.

Step 3: Record

Scientists rely on detailed records of their predictions and the outcomes of their experiments. To record your predictions, cut out each square on your Object Icons Worksheet and glue them to the Sink or Float Prediction Worksheet.

 Step 4: Object Density Experiment

Test each object, one at a time, by placing it in the middle of the tub of water.

  • Does the object sink or float? Was the result what you predicted or were you surprised?

  • Record what happened using the Object Icons and Sink or Float Experiment Worksheet!

 Step 5: Analyze Your Findings

After you have tested all of the objects, use your recorded observations from the Sink or Float Experiment Worksheet to sort the objects into two groups again based on your findings.

  • Which objects did what you expected? Why do you think that might be?

  • Which objects surprised you? Why do you think that might be?

  • Can you think of other objects that might sink or float?

Science Background

Buoyancy is the upward force exerted by a fluid. We can observe this invisible force by how high the water moves when an object is placed inside of it and how the object behaves when placed in water.

There are two main types of buoyancy:

  1. Positive Buoyancy- this occurs when the density of the object is lighter than the density of the liquid it is placed in. When this happens, the object will FLOAT.

  2.  Negative Buoyancy- this occurs when the density of the object is heavier than the liquid it is placed in. When this happens, the object will SINK.

 Buoyancy affects all objects in the water, from HUGE cruise and cargo ships, all the way down to the smallest duckling.

Sinking and FloatingNatasha ChlebuchQuick Hit, Physics