Just up the road from the theme park corridor on the north side of Orlando is the Science Center. It's just off I-4 on Princeton Street next to the Loch Haven area. The Science Center opened about 20 years ago and struggled for years amid all the mega parks but carved out a nice existence for itself.
Six stories tall with an observatory on top the themes of the different floors changes periodically. Dino Digs and Lights & Lasers are two of the exhibition themes where kids can do hands on exploration with physics and chemistry. They can also visit the lab and look at things under microscopes. There are also electrical and water experiments with which they can amuse themselves.
My favorite exhibit is the Dino Digs. Dozens of fossils behind glass are displayed in this room. There are employees and volunteers all over who are there to speak with visitors and to discuss or explain the science and history of the dinosaur periods.
The Science Center is geared for school age kids but all ages enjoy this place. It's educational for everybody and a great family experience. There are playgrounds for the little kids and when you go make sure you secure reservations for the 6-story Imax Theater. It's always awesome. Check the website for shows and times.
Also check for admission and pricing. If you're from the area the best price is the annual family pass for $135/year. This price includes a free parking garage and discounts at the gift shop and cafe.