I'm a high school teacher and I recently was discussing this. Protip: don't talk to 14 year olds about how if something is in between hard and soft, it's firm. đ
I'm 41f (going on 13 at times), and this is why my husband hates(loves) having me around the shop - all the mechanical everything is full of euphemisms and innuendo. "mating surfaces" đ
I had a physics teacher who measured something against his hand in front of class and started to say, "You should try to..." then stopped before telling us he almost said "you should try to use your body to measure whenever possible" but stopped because he remembered he was talking to a room full of high schoolers.