Depends in what context la. Is it for daily basis (home school) or occasional (one off)?
Daily basis need to plan gaogao, worksheets printed out, proper subjects being thought/exposed from time to time. It's not easy but i have a few friends home schooling their kids.

But as a father, occasional ones; like if i have to look after the kid while the mother goes out for 1 whole day, for me are pretty easy because im a little childish to begin with. So i also join whatever my boy wants to do. Drawing/coloring, cycle outside while i jog, playground, cook together, play with puddle when it rains. All these can kill time really easily.