What are overfitting to teachers?

"Overfitting to teachers is when students learn something too well for just one teacher, and it doesn’t work as well with other teachers."

Imagine you're learning how to draw a cat from your art teacher, Ms. Luna. She always wears blue socks and draws the cat with 4 whiskers. You practice so much that you can draw the perfect cat, just like Ms. Luna's, every time.

But then, your friend tries to draw the same cat from another teacher, Mr. Phoenix, who wears red socks and draws cats with 5 whiskers. Your friend gets confused and doesn’t do as well because they were used to Ms. Luna’s way.

That’s overfitting: you’re so good at drawing a cat just like your art teacher, but not as good when the rules change, or the teacher changes.

It's like learning how to ride a bike only on a smooth path, and then getting wobbly when you try it on bumpy roads. You've learned the specifics of one situation too well, and that makes it harder to adapt to new ones.