I would like to have a bathroom break please. But your teacher would not be insulted with what you said.

There is such a thing as too much information. Just excuse yourself politely, saying you'll be right back. Your purpose should be obvious.

Next time just raise your hand and say, "May I be excused?" The teacher will understand. If you were at someone's house, you would say, "May I use your bathroom?" Australians say, " Can you show me where the loo is?" If you were at a restaurant you could say, "Where are your rest room/conveniences?"

You can say: "Please excuse me, I need to go to the restroom." This is a polite way of saying what is needed without too much information :) Hope this helps! :)

can I go to the restroom,please