Came to vote for this. I have bought both 1/18 scale bashers and mini rock crawlers (*) for both my kids and nieces/nephews in this age range and they've all loved them. They are fun to play with and then when you break them you get to take them apart, learn how they work, and fix them.

Just this week I went over to my nephew's house and we ended up spending time diagnosing a burnt out slipper clutch. We worked together to figure out a hack to fix it, and tried it but, alas, we needed a new part after all. A few days later he proudly informed me that he'd repeated all the work we had done by himself, fitted the new parts, and the car was up and ripping again.

* Traxxas Summit 1/18; Traxxas E-Revo 1/18; Traxxas TRX-4M

Some of these RC cars can teach a youngster like this a lot!

https://traxxas.com/news/how-to-rebuild-ultra-shocks