Suzette Kliewer, the teacher who administered the Digital Millennial program at Southwest High School in Jacksonville, N.C., said the phones excited her students and made them collaborate and focus on their studies, even outside of school hours. “They took average-level kids and made them into honors-level kids,” she said.But Ms. Kliewer also said that she spent much of her own time at night, and during weekends and holidays, monitoring the students’ phone use and occasionally disconnecting phones remotely when students broke the rules.“You have to be willing to put in the time and be very patient with the technology,” she said.