KHOU screenshot by Chris Matyszczyk/CNET

School discipline isn't always easy to enforce.

Force, however, has rarely seemed to do all that much good.

So looking at footage of three officers from the Houston Independent School District holding a teen to the floor while handcuffing her is profoundly disturbing.

KHOU-TV, which first aired the footage last week, says it was taken by Gustavo Lucio, a classmate of the teen in the video, Ixel Perez, a 10th-grader at Sam Houston High School.

He told KHOU: "The cops just tackled her down to the floor. They put [a] knee on her head and after that they just arrested her."

What was Perez being accused of? She says she was using her cell phone in class and refused to hand it over. According to KHOU, the school's policy requires students caught using phones in class to relinquish them to administrators and then pick them up at the end of the day after paying a fine.

When the 70-pound Perez was subdued, she allegedly handed over her phone. In Lucio's words: "The cop just said you can't use your phone, and after that, no words, no nothing, just actions: grabbed her, threw her down."

Perez told KHOU that even though the assistant principal had asked her to hand the phone over, she refused because she was scared.

The school district issued this statement: "The safety of our students at Sam Houston High School and of all our schools is always our absolute top priority. The HISD police department and the school's administration are continuing their investigations of what led to the detainment of a female student."

I contacted the school district to ask whether there was something Perez might have allegedly done to warrant such excessive treatment. I will update, should I hear.

The use of cell phones by teens clearly causes enormous consternation for both parents and educators. It seems that teens are permanently attached to them. (Not that this differs too much from adults.)

Perez said that while she was in class she had received a text from her dad and that her mother is sick with kidney problems.

Regardless, how could the use (even if not allowed) of a cell phone have caused adults to behave this way?

What could have happened to incite the scene in the footage? What could possibly make three grown police officers feel they had to subdue a teen in this manner?

Unless, of course, someone overreacted, as has happened in far too many recent (and past) instances.