I love an antique school slate, and think this is a lovely, early one, of a relatively rare small size, with carved wooden nails at the corners that have held the frame together tightly for a very long time. (Earlyish 19th c. I would guess.) It looks to have been owned at some point by an Elsie whose last name is a bit of a challenge to decipher, but seems to spread out across two lines as she ran out of space. 

7 1/4" x 5 1/4", very good antique condition, sturdy and sound, beautiful dry wood patina, no cracks in the slate.