Write on, wipe off … and let the learning begin again! These cards add up to math success! Kids can build their addition skills by completing the equations on each colorful write-on wipe-off card. Just one quick sweep of the pens eraser—and the marks are gone so youre ready to practice again. Because the cards are color coded to indicate difficulty, kids can work their way up as they master harder and harder problems. The pack includes 40 cards, plus a pen.