Math Problems II Write-a-Mat w/ Crayon Bundle for Ages 5+: Addition & Subtraction - The Straight Edge Series Melissa and Doug's The Straight Edge Learning Mat series let your little loved one practice their new skill on an erasable surface With the included crayons, the mat can be easily cleaned by using a web paper towel. Just let it dry thoroughly before reusing the mat. The entire mat can be cleaned with warm water, soap and sponge, and allow to dry. Each mat comes with 2 sides of activities. For ages 5+