Two greenboards measuring 12.75” × 19.5”. One side is ruled in squares and the other side is ruled in horizontal lines. Chalkboards are used to help the child form letters and numbers. There is less resistance when writing on a chalkboard, and the child can easily erase mistakes. The square-rules chalkboard is used to form and erase one letter over and over until the child is satisfied with the results, and the lined chalkboards are used for forming the same letter over and over, or for writing words.