What many don't realize is that large, circular buttons often contain a pin that itself is circular & wraps around the inside of the metal button.
When those pins are detached from the button's back & straightened, they are several inches long.
That being said, the straightened pin could be easily inserted into the teacher's ear and fist-hammered straight through to the opposite ear (John Wick style, like he drives blades deeper into his opponents).*
I'd certainly love to see that (or something close to it) on You.Tube!
[*Source: Tips by Heloise, combat edition]