Great for teaching and practicing fundamentals at the early learner stage. Classic green board contains 5 sets of white headline, broken midline and baseline format. Each line set measures 1 3/4" . Boards feature a high-quality, chalk surface with rounded corners and smooth edges for safety and comfort. Hardboard backing is warp and chip resistant. For best results prime the chalkboard surface by rubbing the entire surface with the side of a chalk stick, then erase completely. Each board measures 12" x 9" x 0.125" .