I have successfully used a "prayer tree" (an idea I got from a workshop).
I attached a large paper tree to a wall. The "leaves" of the tree changed each month. (September was apples, October - pumpkins, etc).
I had the kids write their prayer on the "leaf" and date it. The leaves were stuck on the wall with tape. When the child felt the prayer had been answered, I had them write the answer on the back of the leaf. Then, I had them place the answered prayer at the base of the tree. After several months, they could see how many of their prayers had been answered, and in some cases, had not.
I used this with a confirmation class, and other classes that saw it wanted to take part in it also! Anything visual that is easy to track would work: ice cream scoops, build a sandwich, use clothing-shaped papers and fill a laundry basket, etc. A company called Shapes, Inc has note pads in a variety of shapes. That way you don't have to cut anything out!
Julie Burton, DCE
1st Presbyterian Church, Sapulpa, OK