Surprising things that float?

Question

I am writing a lesson plan about things that float and sink and I was wondering if anyone had any cheap or free ideas of interesting or surprising things that float.

Answer 1

I have done a density demonstration where the students have to predict which fruits will float and which will sink. I let the students examine the fruit beforehand then predict the outcome.

apple

banana

cantaloupe

orange

lemon

coconut

lime

Interestingly, a regular lime will float but a key lime will sink. It has to do with the thickness of the rind.



Another thing you can do is put an unopened regular soda in water and an unopened diet soda of the same type in water. Have students predict beforehand. The diet soda floats. It has to do with the fact that artificial sweetener is so much sweeter than sugar that you need less of it per volume. The regular soda is more dense and will sink.

Answer 2

Put a penny in water, and have the kids watch it sink. Then take some aluminium foil and shape it into a rowboat and place the penny on it. The students will see it floats.



You could also try the classic diet coke vs classic coke. Because there is no sugar in diet coke, it floats, while classic coke sinks

Answer 3

Pumice stone is a rock that floats. Make sure you test it first though. Some samples might actually sink.

Answer 4

check the david letterman archives, a few years ago they had a segment called "will it float?"