I always keep an eye out for beautiful old school slates, and specifically ones that have been personalized one way or another (or mended and mended again.) This one, late 19th century I would guess, has held together very well, no mends required, but was used by at least two different students, who left their initials carved into the frame. (It looks to me like MDW on one side and N, plus maybe also a a PF on one long side, an a few other more ambiguous carved marks, too.) Jointed corners are held together with nails, no glue, and there is a hole at the center of the top for threading a string or ribbon to hang. One side of the slate shows a patch of horizontal lines scratched across the center, which I personally really like.
11 5/8" x 8 1/4" x 9/16. Great structural condition, very sturdy and stable, and completely usable still.