Kid, suddenly, while we're on a walk:
"I want to learn Lua now"
Any good and fun interactive Lua tutorials out there? He enjoyed Scratch because in a visual language everything is discoverable, so he could teach himself while staying within the tool and only going to YouTube when something was extra tricky.
He found some promising tutorials within Roblox itself, but they turned out to have internal consistency issues, like asking you to create a local variable without first having explained the concept and syntax.