Nathan Grigsby, a former teacher at Southwest DeKalb High School, testified on Tuesday. He said he stopped the striptease and simulated sex in his classroom as soon as he noticed it.
Grigsby said he was helping another student during most of the 68-second performance in December 2008.
WATCH: Controversial Chorus Strip Dance
Prosecutor Robert James said the teacher can be seen in a video watching the dance and smiling.
The jury began deliberations on Tuesday.
Grigsby is charged with contributing to the deprivation of a minor. If convicted, he faces up to five years in prison and a fine of up to $5,000.
The three students in the video also face charges in connection with the dance routine. They are charged with public indecency and disrupting a public school.