Back to school gadgets? When I was in elementary school the only thing that might have qualified as a back to school gadget was a pencil case (there was a zipper that moved), or, even better, the protractor inside it (I could adjust the instrument's spread).
Actually, there was, and still is, the combination padlock for the school locker. It was cool: after closing the lock you could open it again just by spinning the center spinny thingy in the right directions and in the right increments.
Some things stay the same. Even with great advancements in technology.
Next: My Texas Instruments T-1250 pocket electronic calculator. (Just $25.00 ― in 1975 currency.)