Yesterday me and Jemima did and experiment called dancing raisins. We got the experiment from a link in the Usborne 100 science experiments. We put bicarbonate of soda, vinegar, raisins and water into a glass cup. We also added red food dye, but we couldn't see the raisins as well. After a few minutes the raisins where covered in bubbles, (the carbon dioxide,) and the floated up and down in the glass.
We put some raisins in a glass full of water, and they stayed at the bottom, because the raisins are denser than the water. But the carbon dioxide in the bicarbonate of soda in the other glass make the raisins float.