Stegno for Kids

I was at a birthday party for a nine-year old niece. She got some dolls (ugh), a Sega Game Gear Game called "Out Run" (not bad) and Crayola brand secret writing pens (WOW!!!!). There are about 8 pens in the set. You write secretly with two of them and develop the image with the other six. I believe the 6 developing pens create images in different colors, but I'm not sure. It just wouldn't look cool for me to rip open the package at SideShow Pizza and hog her gift. Then I had to go. Alas... -Peter