My DS did this in first grade, and I sent him in with 100 Boxtops for Education. We had been collecting them, and it was time to send them in anyway! His teacher thought it was a good idea!
I just remembered I think he did it in 2nd grade too...We took a picture of him outside, in his coat and hat, at night, pointing up to the sky. We cut around the picture, glued it to black posterboard, and he put 100 star stickers on the poster board. We used some of the stars to make the number 100. It was cute...it looked like he was pointing to the stars. His teacher loved it!!

I just remembered I think he did it in 2nd grade too...We took a picture of him outside, in his coat and hat, at night, pointing up to the sky. We cut around the picture, glued it to black posterboard, and he put 100 star stickers on the poster board. We used some of the stars to make the number 100. It was cute...it looked like he was pointing to the stars. His teacher loved it!!