Label your jigsaws!
Big boy went quietly over to his new (to him, I got them from eBay) set of jigsaws earlier and set about completing them, all by himself! I realised I hadn't marked them like I normally do, before I give them to him. So I quickly grabbed a pen and used different shapes to indicate which jigsaw was which. Much easier than trying to keep them in separate freezer bags which I have tried before, as they always get mixed up!
This way, it's part of the game to sort them before you start the jigsaw!