We all have been teaching in the schools where they replaced the regular desks with those rediculously small school house desks. The 20" boards fit on them, but the pieces always fall off the desks because there is no extra space. This is why I brought in the 17" Boards. The full size sets still fit on them and they leave enough room on the desk to store the pieces. These are also great if you are at the coffee house and they have those tiny tables.
17" x 17" with 1-3/4" squares