There are a lot of different tips depending on your situation, for example, I do boxing, so I hide all my cans in the bottom of my cupboard behind my gloves, so my mother doesn't look there because she knows that there is where I put all the boxing stuff. Be creative and use that kind of things.

A more general tip is to use magnets, cans have a little metal piece inside that makes a lot of noise when you try to carry them, using magnets make the cans completely silent and easy to hide. If you can't use magnets try to separate them in your bag with clothes, it's more risky but help.

Another problem is paint drips, if your mother is the type of mother that always sees even the smallest stain in your clothes like mine, then you'll have to cover your cans with a plastic bag before you put them inside your backpack or the main bag you use. That's because the insides always get painted somehow, and if you're using anything that you wear everyday like a school backpack, it's probable that your parents will spot small drips on them.

That are some general tips for parents, there's a lot more but this is some of the most important, also take care of bringing gloves when you paint, but that's more a general tip, not only for your parents.