Was it possible to give up? In my place, they wouldn't be let on to the next grade if they'd fail basic math - i.e., they'd spend the summer repeating it + an extra year in the same grade if that wasn't enough; so it would have to be a real exception to see a 10 year old who can't somehow manage that.

Anyways, the classic mnemonic for that was simple - for < and > the wide part contains more 'thingies' than the narrow part. They're actually taught before numbers or together with numbers, like [pic of four strawberries] > [pic of three strawberries].