@Jess I’m nervous he’ll eat the crayons he’s only 15 months
He will try but you just have to redirect him to continue drawing. Using crayons at this age also helps their fine motor skills so you'd be keeping things fun while also helping him learn. My son has been playing with toddler crayons since he was 12 months. He still tries to put them in his mouth from time to time even now but we just redirect him and he continues drawing. The dog on the other hand....ate 2 of them lol.
Maybe find him some new water toys to keep him interested in baths. When my son has a rough bath night, we bring out the bath crayons. He loves them and they are easy to clean with a disinfectant wipe.