Located in the old court house in Redwood City you will find San Mateo County Museum.
This little museum (that is not bigger than both kids and elderly may enjoy it) has exhibits showing the development from native Ohlone tribes over ranches and orchards to the Silicon Valley as we know it today.
Particularly for the younger and those not familiar with the agricultural past, the museum has an instructive collection of rural tools. It has a great video on the railroads in the area and the impact on development, a beautiful collection of artifacts from the many immigrants from all over, and naturally the court room where you will have a rare chance to act judge.
As we take modern conveniences ever more for granted, this museum offers a glimpse back in time and a reminder to what a world without electricity had to deal with.