PreK scientists completed their study of the pond and are currently in an ocean unit. This lab focused on the difference between salt water and fresh water, as well as understandings about why some things float, but others sink.
We mixed salt into one of two cups filled with water. The salt dissolved and formed a solution. When we dropped the bead into the salt water, it floated but the beads sank in the cup of fresh water. Look at what happened when we dropped food coloring in the cups. Why does the coloring float on top of the salt water? Then we dropped raw eggs into salt and fresh water.
The children shared their ideas about why some things float and others sink. Most believed that objects that are big or heavy sink. Also, things with holes in them sink. They made a hypothesis before they each dropped an item into the tank. When our hypothesis didn’t match the results, we learned something new and that made us rethink our original ideas. (Notice that the larger things are floating.)