And the winner is....
My son with the EXACT guess of 3 inches.
I did not notice that these were the smallest growing alligators and that the record growth is 5 inches so I was way off with a guess of 10 inches. I was beat by a five year old, a smart one. Next time we will try purified water and see if we can get it to grow over the 3 inch mark.
Way to go kiddo!