Floating and Sinking

This week we have been busy investigating things that float and things that sink. We are becoming good at predicting accurately what will happen (will it be a floater or a sinker?) before we try it out. When we tried to push an inflated balloon under the water it wouldn't stay under the water when we let it go again. This push force is called upthrust and this is what helps to make objects float. The inflated ballooon floated because the upthrust from the water was stronger than the weight of the balloon. Some of the objects we tested (like the stone and the metal spoon) sank straight away as the weight of them was stronger than the upthrust of the water. It's fun investigating and we could do it outside as the weather was lovely.