Hey, why are those stuffed animals floating around in the pool? Well, because they can. They’re floating on little boats made of aluminum foil. Foil is thin, but it holds up the animals just fine. When you float something on a boat, the boat will sink just enough so that the water it “displaces,” or pushes out of the way, weighs the same as that object. If something weighs 1 pound, the boat will sink enough to push 1 pound (16 ounces) of water out of the way. If the sides of the boat are too low, the water will gush in over the top! But if the sides are high enough, then the boat floats. So if you want your furry friends to stay dry, just do the math. Weigh them first. Then test your boat with the same weight of pennies or rocks. That way you don’t have to have any sinking ships.
Wee ones: How many stuffed animals are floating in the pool? Look closely and count them!
Little kids: If the 3 lobsters each weigh 2 ounces, how much do they weigh together? Bonus: If the caterpillar weighs 9 ounces, how much more does he weigh than the lobster triplets?
Big kids: 11 pennies weigh about 1 ounce. If you need your boat to hold up a 5-ounce teddy bear, how many pennies does it need to be able to carry? Bonus: If you want to carry 5 of those teddy bears, and you’re testing your boat with 7-ounce rocks, how many rocks does it have to hold for you to know it can carry the bears?
Wee ones: 4 stuffed animals.
Little kids: 6 ounces. Bonus: 3 more ounces.
Big kids: 55 pennies. Bonus: 4 rocks. The boat needs to hold 25 ounces, and 3 rocks will only prove that it can hold 21.