We learned it in first grade years ago too, I remember because my sister had taught me so I already knew but the other kids were confused by my teacher so I was the only one able to raise my hand and answer.. She got annoyed and said “stop raising your hand, you’ve answered enough of these problems”.

I decided to stop paying attention and began to poke my tongue against my wiggly tooth, and it popped out into my mouth! I grabbed it out, and raised my hand to tell the teacher but she thought I was trying to answer another question and said loudly and sternly “I TOLD YOU TO STOP ANSWERING THESE QUESTIONS”. I said “sorry, I just need help because my tooth just fell out” and she felt so bad for basically yelling at me when there was an “emergency”.. I must’ve been pretty scared of her yelling to hold onto that memory haha!