SciShow Kids is essentially the modern successor to Magic School Bus or Bill Nye, but built for the short-attention-span era. It’s one of the few corners of YouTube where the production value is high and the educational intent is genuine.

If you're going to let your kid on YouTube, this is the first channel you should subscribe to. It avoids the 'brain rot' traps of loud noises and bright colors for no reason, opting instead for actual substance that might actually help them in first-grade science class.