Sinking and Floating

Grade 3 has completed some lessons on sinking and floating. We discussed buoyancy and made some guesses about which fruits or vegetables would float or sink. We saw that raisins sank. When we put raisins in bubble water they floated to the top and then sank. We observed bubbles of less dense air forming on the bubbles and causing them to float. When the bubbles popped at the surface, the raisins sank again. 

We made Cartesian Divers. We saw that squeezing the bottle changed the size of the bubble in the diver and caused the diver to sink. A lot of really tricky science can explain this but just understanding a little bit about density can help the kids to figure out how the divers sink and float. 


We made foil boats and tested how much weight they could hold. By observing their boats and the boats of their classmates, students could make suggestions about how to make a better boat. This was quite exciting and it seems like students could build boats all term. 

Learning goal: Testing ideas using evidence from observation and measurement