The Perot Museum is a great place for families. There are plenty of interactive exhibits that will keep children entertained for hours! The Leap Frog Forest is a good place to visit after you go through the museum. The water feature is a wonderful place to cool off on a hot summer day. The frogs provide a good place to take some funny photos. The cafe, Leap Frog Forest, and gift shop are accessible without admission.
The lobby is where school groups gather, and occasionally local businesses set up tables to share how they contribute to science. Once inside, I recommend taking the escalator to the fourth floor and working your way down through the museum. The escalator moves past the big window, and provides one of my favorite views of the city.