Girls try and identify different types of chocolate
Before the meeting, melt various different types of chocolate (e.g. dairy milk, tesco, galaxy..) and pour into moulds to make a selection of small chocolates (Lakeland sell moulds, or use an old advent calendar/ chocolate box tray). Ensure all are kept labelled!
During the meeting, anonymise each chocolate (e.g. A, B, C..) and pass round for girls to try. They can either have the list of what's been melted down, or try to guess without the list. You could always throw a few red herrings into the list.