Hi M.,
I am in a similar situation. My son is 2 1/2 and I too was a teacher in my previous life. We have found a few fun and educational places around town that we like to frequent.
The Botanical Gardens are great when the weather is nice. Mid October is the monarch butterfly migration - there are caterpillars and butterflies everywhere!
And the Ft Worth Modern Art Museum is free on Wednesdays. You may want to double check what exhibits they have running before you go - they are not always kid friendly, depending on your comfort level. I have been pleasantly surprised that those visits have gone well. I think and hope he is learning how to behave in a museum. Sometimes we bring snacks and go eat outside near the water for a break. And he loves to hear the echoes in the sculpture out front!
Toddlers get in to the Fort Worth zoo for free and Wednesdays everyone gets in half priced. If you bring a lunch it can be a cheap and fun date.
Admission to the Dallas Museum of Nature and Science costs $9 for adults, but toddlers are free. They have a terrific section just for children that includes water play, dress up, building and nature. But my son was just as fascinated with all the exhibits we saw throughout the museum. They have a dino dig that is especially nice, because it is inside.
Both the Keller rec center and Roanoke rec center offer some great classes at reasonable prices (even for non-member and non-residents). We have taken several swim classes at Keller and been very happy. And we have taken two gymnastic classes at the Roanoke center. The woman who runs the class is amazing and she has been teaching pre - K gymnastics for over 20 years. She incorporates counting, colors and language arts into her lessons. Not to mention teaching little things like sharing and waiting your turn.
We frequent parks, trying new ones throughout the area. If I get desperate we have even been know to go to Cabela's just to check out their fish aquarium! And Ridgemar Mall has a great toddler play area.
Hope this helps! Enjoy the time home...I know I have!