Parents: what are the gift-giving norms at elementary schools?

NYC parents only please!

My coworker recently arrived in the U.S. and is learning English. She has two small children. She says an American parent told her that she needs to get flowers for all of both of her children’s teachers for Valentine’s Day. (6 bouquets total.)

This seems like a bit much to me but I don’t have children myself so maybe I’m missing something? Could this be correct?