1905: Stereoscope.

The ancestor to the ViewMaster, this device brought the wow! factor into the classroom with 3-D. The stereoscope had been around since the mid- 1800s (Queen Victoria was a big fan). But it wasn’t until the early 1900s–when stereoscope manufacturers started hawking the device to teachers–that it make its way into the classroom. 3-D has come a long way since then. But the glasses–not so much.