General Science PreK-2nd Extension Activities Lesson 3

Buoyancy

Test in Corn Syrup and Vegetable Oil - 01:15

Test the same objects from the lesson, but in corn syrup and vegetable oil. Buoyancy depends on the properties of both items.

Salt vs Fresh Water - 02:05

Make a cup/bowl of salt water (1 cup water: 3 Tbsp salt). Make an equal cup with fresh water. Test objects to see if they float: plastic building block, raw egg, grape, coin, shell, gummy candy. For an additional cup to extend the test, add a cup with a similar amount of baking soda mixed in, or try corn starch or other powders.

Cartesian Diver - 04:53

There are many variations of this project. The most simple version is to use a plastic bottle (2L is a bit easier to see, but could be a smaller bottle). Fill almost full with water. Insert a condiment packet (duck sauce is a common suggestion because it's clear and has a good air bubble in it). Fill the bottle completely with water and screw on the lid. Squeeze the bottle and the packet should sink. Release and it will pop back up. This is how fish swim bladders work. The pressure compresses the air bubble and makes it more dense which makes it sink.