NEW YORK (AP) — A former math teacher at an upscale private school in Brooklyn and one-time “Jeopardy!” champion was sentenced Wednesday to seven years in prison on charges that he posed as a teenager on Snapchat to solicit nude images and sexual videos from children.

Winston Nguyen, 38, had pleaded guilty earlier this month to one count of use of a child in a sexual performance as a sexually motivated felony and five counts of endangering the welfare of a child. He will have to register as a sex offender after his release.

Prosecutors said Nguyen, who taught at Saint Ann’s School in the tony Brooklyn Heights neighborhood, pretended to be a teenage boy on Snapchat and himself sent nude images and videos to children and got the children to send illicit material back to him.

The children, who went to various schools in the city, were between the ages of 13 and 15 when the messaging occurred.

“This was a sickening betrayal of trust by a schoolteacher who solicited students into sending him graphic and nude photos,” Brooklyn District Attorney Eric Gonzalez said in a statement.

In an email, Nguyen’s attorney, Frank Rothman, said his client “expressed true regret for his actions today and offered to engage in whatever restorative type healing process that the families of the students may suggest. But he understands that most likely it would not happen.”

Nguyen appeared on “Jeopardy!” in 2014.