> We plan to do some more complicated robots and also make our own fun mods for Minecraft (as soon as I figure out how to hook up Scratch to recent version of it).
You can't quite hook up Scratch itself to Minecraft (not that I know of, at least), but if you want to use Minecraft as a backbone for this kind of education, you might be interested in Pneumaticcraft, which includes little programmable drones that are programmed using a simple mockup of scratch (https://www.curseforge.com/minecraft/mc-mods/pneumaticcraft-...) or ComputerCraft, which tries to emulate shell scripting and lua in particular (https://www.curseforge.com/minecraft/mc-mods/cc-tweaked). In the future, if you wanted to teach him Java, you could have him develop mods himself through the Spigot, Forge, or Fabric modding APIs.