Unit E: Describing Matter

A big tugboat floats in water. Will a pumpkin float in water?

1. Get Set to Explore


  • property: Anything you can learn about an object by using your senses; sinking and floating are properties of objects.

Building Background

  • Review the definition of property with the class. Ask children to name different properties of common objects. Guide them to understand that whether an object sinks or floats in water is a property of the object.
  • Have children recall different experiences they have had with objects sinking or floating, in a bathtub or a swimming pool, or during a classroom activity, such as the one on Student Edition page E3. Elicit functional definitions of floating and sinking: objects that float stay on top of water; objects that sink drop to the bottom of a container of water.
  • Through class discussion, work with children to make a list of factors that affect whether an object floats or sinks. Write these factors on the board for children to refer to as they do the simulation. An object's weight (density), its shape, and whether or not it contains air are examples of factors that influence whether an object sinks or floats.
  • Have children each make a chart with space to record the names of 12 different objects. For each object, they should record a prediction about whether the object will sink or float, space to record whether the object sank or floated in the simulation, and the reason the simulation gave for the object sinking or floating. If you wish, you can make such a chart for the children, photocopy it, and hand it out before the children do the simulation.
  • Read the Discover! question to the class: A big tugboat floats in water. Will a pumpkin float in water? Direct children to record their predictions in their charts.

2. Guide the Exploration

  • Let children launch the Discover! Simulation. Tell them to listen closely to the question and the directions.
  • Have children use their charts to list the different objects shown on the screen. For each object, children should predict whether the object will sink or float, recording their prediction in their chart. Children may enjoy working in groups of three to do this simulation.
  • After children have made their predictions, direct them to drag each object, to the tub and release it. They should note whether the object sinks or floats and what explanation is given for this.

3. Review/Assess

  • Go over the results with the class, with volunteers reporting the results for different objects. Children should note that the following objects float in water: balloon, basketball, beach ball, crayon, Popsicle® stick, pumpkin, shoe; children should note that these objects sink in water: clay ball, golf ball, marble, metal paperclip, penny, potato.
  • Review Step 3's Wrap-Up text with the class. Emphasize the importance of the air space in helping to explain why the pumpkin floats. Guide children to name other objects in the simulation that float in part because of the air spaces they or their materials contain: balloon, basketball, beach ball, shoe.
  • Present the Extension question to the class. Let volunteers share their ideas with the class. Possible ideas might be to flatten the object, reshape it, or change it so that it includes one or more air pockets.

If time permits, present children with the following question or activity:

  • Critical Thinking Analyze How can an object that floats aid a swimmer who is in trouble? How can an object that sinks aid a diver? Answer: The swimmer can hold on to the floating object to help him or her stay on top of the water; the diver can hold on to the object that sinks to make it easier for him or her to dive down under water and to stay under water.
  • Inquiry Skill Predict Pick four or more objects in your classroom or in your home that will not be damaged by water. Predict whether they will sink or float. Record your predictions and test them in a sink or tub of water. Answer: Answers will vary depending on the objects children choose; objects made of plastic and wood generally will float; those made of most metals will sink.

4. Reaching All Learners

On Level: Visual Learners and Kinesthetic Learners

Give children a bucket full of water and encourage them to test their predictions of either the objects in the simulation or the objects they made predictions about in the Inquiry Skill activity, above. Make sure children record their results. Watching the objects sink or float and taking them out of the water can help reinforce children's learning. Make sure to give children towels, so that they can dry their hands.