Step 9: Remove Crayon Marks from Walls
If you read step three then you can understand why this makes sense...
Crayons are made out of wax, blow dryers remove wax, thus blow dryers remove crayons.
Set the hair dryer on hot and keep it on the crayon mark until it melts. The crayon will wipe off easily with a damp cloth and a small amount of oil soap cleanser.