This app was mentioned in 6 comments, with an average of 3.17 upvotes
Try falling sand games, like this one - https://play.google.com/store/apps/details?id=com.singlecellsoftware.sand
It's a neat little sandbox. You pick an element and draw stuff with it on screen. Also elements interact with eachother (put water on plant and it'll grow, add fire and it'll burn etc.)
(Just in case you'd consider something a little different)
My 5 year old really likes Sand! and she has the free version. I've never seen ads. You have a drawing/building space and about 18 elements like sand, wood, cement, water, fire, lava, methane and nitroglycerin. When these elements come into contact with each other, they have the expected reactions. She likes to draw things to protect from the lava flows and explosions as much as she likes making the big reactions. When burning things fall into water steam rises and, well you get the idea. It really didn't take long at all for her to get the feel for what everything was and her imagination took off. It's not exactly a game, but fun all the same.
Edit: here it is. https://play.google.com/store/apps/details?id=com.singlecellsoftware.sand
My son really liked this little falling sand game I made a while back. This one is free and there's a 1$ premium version with more elements to play with.
Not really "educational" but good for developing their imagination.
https://play.google.com/store/apps/details?id=com.singlecellsoftware.sand
Sand! https://play.google.com/store/apps/details?id=com.singlecellsoftware.sand
One of my favorites, haven't played it in a while but when I do play it it's so fun.
Physics Simulation Building Destruction https://play.google.com/store/apps/details?id=jp.webnode.mountainrooting0.buildingdestroy
Shoot balls at structures and watch them fall. So fun.
here's a high-quality one for Android devices: https://play.google.com/store/apps/details?id=com.singlecellsoftware.sand&hl=en ...made by the developer of Caustic 3, which is essentially "Reason Mobile" (for Android).
the free version has a lot of options, and the paid one even more.