I've bought and sold a lot of old school slates, usually attracted by the often mended (and best of all carved into) frames on very antique ones. In this case, though, it is the slate itself that sold me, one side etched with a grid, as one sometimes sees, but more unusually the other with angled guide lines of varying widths, designed for practicing cursive writing at just the right slant I believe, both in capitals and lower case. And that side especially on this slate was much used, with the traces of lots of letters lightly scratched across its surface horizontally.
12" x 8 3/4" x 3/8". Frame in very good condition and very sturdy.