Hey man,
I'm doing a kid's show on the 11th and was viewing this thread for an idea to get little kids started in magic.
I don't know about this crayon trick either. Why don't you just post what happens in the trick instead of pming him all secretly . . . . just like a magician to do that.
I think that the floating cup is probably your best bet, but one trick that I remember learning in first grade was "Magically Multiply your Money". I remember doing it with pennies and nickels back when my hands were smaller, but I think that most 1st graders should be able to perform it with quarters easily enough.
Im glad I can inspire and help my felllow comrads...also have you thought of the dissapearing toothpic/piece of paper trick, the one where its taped at the back of the thumb?