Easy Clean Window Crayons
I have to say I was skeptical about these crayons actually coming off easily before we got them, but they really do. The colors are bold and they glide smoothly.
And then, even if the drawings have been up for many days, it comes right off with a wet wipe. You'll still need another round of wiping with another cloth or sponge depending on how much is on there, but you don't have to use much muscle and the child can do it on their own too.
Super fun if you have glass at child height in your home. Price is for a set of 10 w/ sharpener.