Magic eraser

You gotta check this out. We have our wall back with just one use. Not sure what it's made of but all you have to do is wet the sponge and gently scrub your walls. Crayons, pencils and smudges will be erased. Heed the "gently" seriously. It does leave a cakey feel if you scrub too hard. It costs $2.19 and comes in 2. Small price to pay to have your walls clean and presentable again.