In California, a high school teacher complains that students watch Netflix on their phones during class. In Maryland, a chemistry teacher says students use gambling apps to place bets during the school day.

Around the country, educators say students routinely send Snapchat messages in class, listen to music and shop online, among countless other examples of how smartphones distract from teaching and learning.

The hold that phones have on adolescents in America today is well-documented, but teachers say parents are often not aware to what extent students use them inside the classroom. And increasingly, educators and experts are speaking with one voice on the question of how to handle it: Ban phones during classes.