This is musical chairs with an exciting difference - very popular with younger kids!
Cut a large circle of paper, old sheeting or old plastic tablecloth for every child at the party, and draw on large bright numerals. You have also prepared a few small prizes, one for each round you are going to play, wrapped up and marked with corresponding numbers. So, for example, if you have 20 children and hope to play 5 rounds, you would have 20 pieces of paper marked 1 to 20, and say 5 prizes marked 3, 7, 12, 15 and 19.
Scatter the papers around the room and get the children dancing as before. When the music stops the children must sit down on a piece of paper. Then, with a big fanfare, announce the "magic number" for that round and see who has won the little prize!