Lesson 3 Science

Buoyancy

http://edweb.sdsu.edu/triton/JGarciaResearch/LessonTemplate1.html

by

Jackie Bonventre
Russ Nielsen

Objective

The students will understand how things stay afloat.

Direct Instruction


For some added flavor to start the lesson wearing a sailor's hat and say, "Hello Maties!" You can also ask questions such as, "How many of you like to swim?" and "Have you ever been on a boat?"] Both of these would lead to buoyancy. Explain what buoyancy is by drawing a picture of a boat on water on the whiteboard. You can use arrows to show the weight of the boat pushing down and similarly use arrows pointing upward to show the weight of the water pushing the boat up. When these arrows cancel each other out, the object on the water becomes buoyant or floats.

Lab

The weight of water has a lot to do with buoyancy. Bouyant things displace the amount of water equal to their weight. Sinking things displace an amount of wather less than their weight. But does the weight of the thing have anything to do with whether it floats or sinks?
Materials
  1. Piece of clay
  2. Big bowl of water

Directions
  1. Take half of the piece of clay and mold it into a small boat shape.
  2. Mold the other half of the piece of clay into a ball.
  3. Put the boat into the wather
  4. Put the ball into the water

Discussion

Shape has a big effect on buoyancy. Both the boat and the ball have the same amount of clay, but their shapes are really different. The boat displaces an amount of water equal to the weight of the clay, but the ball doesn't.

Homework

The students must write a summary of what happened during their lab. They must include an explanation of why this occurred.

Last updated May 17,1997.

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