Fun on the Trampoline

What does an 18 month old little great grandson do on a trampoline?  He loves it.  But just look at the concentration on his face as he tries to walk on it.  It is so cute.  He has so much fun with his sister and brother.  They can all 3 play together on the trampoline.  They are growing up so fast.  In a couple days school will be out and then they will be able to play together every day.