Relating Buoyancy
By Jamie Pine
University of Idaho

ITV Series:  Bill Nye Science Guy, Cut 2, Buoyancy, #119FD01011_.WMF (6418 bytes)


This lesson is designed to teach the students about buoyancy. The students should be able to discover whether or not a section out of James and the Giant Peach is reality or fantasy, using the information they learn about buoyancy.  A great lesson to complement a "Sink or Float" unit.

Learning Objectives

Students will be able to:

  • Explain what causes objects to float and identify the characteristics of an object that floats.
  • They will predict whether or not a peach will float and conduct an experiment to prove whether or not their prediction is correct.
  • Students will analyze the qualities of James' peach, and tell whether the story is reality or fantasy.


Per every 2 students:

  • One bowl of water
  • peach
  • penny
  • marshmallow
  • paperclip
  • piece of paper
  • rock
  • apple
  • Handout

Pre-viewing Activities:

Reading:  The students will have read through chapter 19 of James and the Giant Peach.
Possible discussion topics:  When James, his friends, and the peach went under the water, what did you think would happen?  What made you think that?  What makes objects float?  What is a prediction?  Do you think that a peach could really float or is that just a fantasy?  Have students record their predictions on the top of their handouts.

Focus for Viewing

To give students a specific responsibility while viewing, have students predict what makes an object float and whether they feel that a peach can really float or not. Students will need to fill out  handout while viewing the video. The video will answer all the questions that are located on the sheet before the experiment.

Viewing Activities 

START: where Bill Nye is driving down the road and says "The reason why things float or sink."  PAUSE: After Bill Nye says, "The weight of water is what makes things float."
Have students answer the first question on the handout: What makes things float?  Fast forward: to where DISPLACEMENT comes up on the whole screen.  START: from displacement  PAUSE: after Bill Nye says, "In fact everything you put in water displaces water."
Have the students answer question #2 on handout: What is displacement?  Fast forward to after Bill gets out of dunk tank and starts to pick up the boat.  START: from Bill Nye picking up the boat.  PAUSE: After Bill Nye says it just balances. 
Have the students answer question #3 on handout: The object in the water and the water it displaces are which of the following?

  • Equal in weight
  • Object weighs more
  • Water weighs more - discuss what happens when you get into the bathtub? 

Fast forward: to part where the child comes on the screen.  START: from the child coming on the screen.   PAUSE: where the child says, "the shape makes a difference."
Have the students consider their predictions of whether the peach will sink or float. If the predictions stayed the same have them copy it to the space that says, "Prediction of peach." If their prediction has changed have them write that there.  Fast forward: to when the word TEST comes on the screen.  START: at the word test.  STOP: after the kids throw Bill Nye into the pool.   Discuss whether or not watching this video made students change their minds. Have students explain their reasons why they kept their predictions the same or why they changed.

Post-Viewing Activities

Inform students that now they know what makes things float, they will be conducting some experiments of their own.

  • Predict if objects listed on handout will float. Record predictions and one reason why.
  • Conduct the experiments.
  • Record results of experiments. Write one reason why your prediction failed if it did.
  • Conclude whether or not the buoyancy of the peach in James and the Giant Peach is reality or fiction. Discuss as a group why the answer is what it is.


  • This video can be used to explore many different ideas in math. Two specific concepts that are dealt with well in this video are concepts in weight and volume.
  • Conduct other experiments.
  • Go swimming and conduct experiments and make predictions of who will be the most buoyant.
  • For additional lesson plans and ideas relating to this topic and many others try TeacherSource!   You will find activities, lesson plans, teacher guides and links to other great educational web sites!  Search the database by keyword, grade level or subject area! 
  • Mathline and Scienceline are also great resources for teachers seeking teaching tips, lesson plans, assessment methods, professional development, and much more!  Look for a localized version of Mathline and Scienceline on IdahoPTV next year!

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