Wolfram Alpha is the internet’s giant calculator that actually went to grad school. While Google tries to sell you a mattress when you search for 'sleep cycles,' Wolfram just gives you the data. It’s the ultimate 'show your work' machine, which is both its greatest strength and its biggest temptation for a kid staring at a pile of algebra homework.
It’s not 'fun' in the sense of a video game, but for a kid who constantly asks questions about the scale of the universe, it’s basically magic. Use the Pro version if you want to nix the ads and see the step-by-step logic, which turns it from a cheating shortcut into a legitimate tutor.