We went to the Thanksgiving Point children's Discovery Garden. I highly recommend this place. They have added so much in the past few years and it is really cool. They have $2 Tuesdays for the month of August so we definitely had to take advantage of the sweet deal. In the front entry of the garden is a giant Noah's Ark fountain area and the kids can go in their swimsuits and cool off in the water. With the deal this month it is super busy so you will get a wristband and time slot on when your kids can play in the water. We arrived at 12:30 and our time slot was 3:40. Bring lots of snacks and water and your camera. We were there about 4-ish hours and didn't even get through all of the gardens!!
There is a wooden xylophone instrument area. Very shaded with lots of benches to sit and rest on.
From what I have read Thanksgiving point has the largest man made waterfalls in the US. There is a long pathway that wraps up and behind the waterfalls revealing many cool water spots.