Three glasses of water
2 tablespoons of salt
2 tablespoons of baking soda
Using the sticker and marker, mark the three glasses of water as 1, 2 and 3
Add two tablespoons of salt in glass number 1
Add two tablespoons of baking soda in glass number 2
Add a few pieces of grapes in each glass from glass 1 to 3 and try to notice the cup in which the grapes float.
How does this work?
You will notice that the grapes in glass number 1, which contains salt water, will float the most. This is because salt water is denser than the grapes which allows it to float.
You will notice that the grapes in glass number 2, which contains baking soda, floats in the middle of the glass. This is because baking soda dissolves in water to release carbon dioxide gas, which does not allow the grapes to sink fully into the glass, which makes it float midway.
You will finally notice that the grapes in glass 3, which contains freshwater, sinks to the bottom of the glass. This is because freshwater is lighter than the grapes.