My contribution was to do an experiment using the chemical reaction between bicarb and vinegar to inflate a balloon (blog post to come soon).
One of the other bloggers (Jaime Reimer at Hands on as we Grow) talked about an easy but visually wonderful experiment you can do by squirting coloured vinegar onto a tray of bicarb. So we had a play.
You just need a tray to sprinkle your bicarb on, some old syringes and a few containers filled with coloured white vinegar.
The girls absolutely loved this and we will definitely be doing it again ... once I've bought some bulk bicarbonate of Soda. the little pots from the supermarket don't last long!