I have an 11 year old grandson and two 6 year old ...

I have an 11 year old grandson and two 6 year old granddaughters (cousins). When they come to visit me, this is their first choice--all 3 of them--for a place to visit. They actually prefer it to the Exploratorium in San Francisco--I think because it is so much more informal and hands on. At the Exploratorium, the technology brings the exploration to you. At LHS, you bring the exploration to the technology. And you don't have to worry as much about ways in which you might (or your grandkid might) damage something. Best kid-sitter in Berkeley.