The cell phone video begins with 13-year-old Isaiah Johnson backed into a corner by his teacher. You can hear laughter and applause in the background. But what students thought was a joke - quickly turned ugly.
Classmate Janiqua Johnson shot the video on her cell phone. She says Isaiah had been making fun of another girl in class - when the teacher snapped.
To watch the video, click on the video link above.
The school now identifies that science teacher as 40-year-old Sheri Lynn Davis. She had worked at Jamie's House Charter School in north Harris County, Texas for three years.
School administrators say they put her on administrative leave when they heard about the incident late last month. Now that they've seen the video, she's been fired.
Despite that, students who saw the beating say they've felt intimidated by some teachers since the video went public. They claim several other school employees saw the incident - and did nothing.
The school is promising a full investigation. The Harris County Sheriff's Office is investigating the incident, Deputy Janie Wagner says.