L OOK ALIKE DOESN ’ T MEAN ACT ALIKE I NVESTIGATIONS WITH BUOYANCY AND DENSITY 5.5A Engage

S TUDENTS NEED TO … Conduct tests, compare data, and draw conclusions about physical properties of matter including density and buoyancy.

G ATHER THE M ATERIALS : Ping pong ball (per group) Golf ball (per group) Plastic cups (per group)

S ET THE SCENE : Show students a golf ball and ping pong ball Discuss the similarities students can observe. This could include color, size, shape, or any other characteristics students notice.

B RAINSTORM HOW TO FIND OUT MORE Now ask students how the balls are different. Present the cups of water which can be used to find out more.

N OW CONDUCT THE TESTS ! 1. Explain that students will find out more using their cups of water and the ping pong and golf balls. 2. Introduce buoyancy as the amount water pushes up on the ball – we see this as how well the object floats. 3. Students can test how the buoyancy of the balls compares. 4. Ask students to verbalize their results – what happened?

T HEN INTRODUCE DENSITY ! 1. Ask students how the buoyancy compared – did the balls behave differently when placed in water? 2. Explain density to the students – if the ball has more particles in the same amount of space, it is more dense. 3. How can we explain our results using what we know about density?

H AVE STUDENTS EXPLAIN THEIR RESULTS ! What happened? Do the two balls differ in how buoyant they are? Is one more dense than the other?

G ET STUDENTS THINKING … What else can we find out about the ping pong and golf ball? What other tests could we conduct to find out even more?