During our STEM activities this week we decided to explore floating and sinking as it would be useful learning alongside our Titanic topic.

Our first activity involved making a prediction to decide if cans of juice would float or sink and why we made this hypothesis. We discovered that the cans of diet juice floated as they were less dense than the cans with sugary drinks. We also discovered that the non-diet juice contained over 18 café sized packets of sugar. After much discussion we concluded that water or milk would be a healthier option.

The next challenge was to make a change so that the floating orange would sink. The groups worked well coming up with different ways to achieve this: trying to squeeze the juice out, making holes in the skin and cutting it into smaller pieces. However the removal of the skin did the trick and Luke was able to explain why. Here’s the science:  Drop an orange into water and it floats, but remove the peel from that same orange and it will sink. The unpeeled orange floats because the rind is very porous and filled with tiny pockets of air. Even though you’re removing mass when you peel the orange, the peeled orange is more dense and sinks in the water.

The final challenge was to make a marshmallow sink and again imaginative ideas were at work. Making it smaller, cutting off the powder coating, squeeeeeezzzing it so hard to remove the air trapped inside. After much strenuous and messy activity the successful team managed to sink a small piece of pink marshmallow by making it smaller and squeezing it flat. We wondered what would happen if we dropped the marshmallow into different liquids such as cooking oil or used mini marshmallows. Further investigations are required.