Each child needs an inflated balloon and a permanent marker (otherwise the pen will smudge on hands!). Write on the balloon things you want to say thank you to God for and then get ready! Play some music and children bat the balloons to each other. When the music stops, they grab the nearest balloon, read what it says and, together, everyone says 'Thank you God for...' The music starts up again and the process is repeated for as long as feels right!
We have used a similar idea in a primary school harvest service and in an all age service. This time we have pre- written 'thank you' on about 30 balloons and the whole congregation has batted the balloons around as music plays. At the end of the music, the leader says a big thank you prayer and everyone joins in the 'Amen'! The school especially loved the idea and talked a lot about how church had actually been fun!!