Shot on a cellphone, the video shows 66-year-old Beverly Round being shoved to the ground by a student at Nimitz High School in Houston.
Round was treated for minor injuries and is recovering at home. "I'm all right, thank you," she told KXAN.
The unnamed student in the video was arrested by campus police and charged with injury to the elderly.
Other students in the class can be heard laughing at Round's plight during the clip.
"You can see her walking past to try get away from it," said a student. "He pushed her twice. The last time, she's on the ground. You see her kind of hit her head going down. Most people laugh. I didn't find it funny."