My kids (ages 5 and 7) and I had a day to kill in San Jose, so we went by the children's museum. What a wonderful surprise! It is HUGE with an amazing variety of subjects and activities--40 rooms in all. It was super cheap, only about $7 for two kids and one adult. It was also very well staffed and easy to find guides to help show us how to work exhibits. (It helps to know some Spanish but certainly not necessary.) There is a small cafeteria with basic, inexpensive food.
My only complaints are that (1) a good number of the activities were broken, and (2) the lighting is so bad in spots that we couldn't see the exhibits. Even so, there were so many other exhibits to enjoy that I still give it five stars. We spent six hours there, and I had to drag my kids out. It is their favorite museum ever and have been asking when we can go back.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.