This is more of a long term project but one that the kids will remember forever. Periodically I have them write journal entiries, prayers, or any other written entry. I have a file of each kid where I store these entries. They really don’t know why they are writing them or what the purpose is.
After they graduate I mail all their entries to them. They have usually, of course, forgotten all about them and find it very interesting to read through them and see how they have grown in the past years. I have found they absolutely love it and it is definitely something they want to hold on to forever. Of course this is only good if you are planning to be at one church for a long while.