It happened at P.S. 723 on Webster Avenue in the Claremont section on Tuesday morning.
Prosecutors say Dana Barschdorf, 44, pulled down his pants and exposed himself in front of six students between the ages of 9 and 11.
He is charged with endangering the welfare of a child, harassment and exposure of a person.
Barschdorf is due back in court on Feb. 14.
The Department of Education released the following statement:
"This alleged behavior is completely unacceptable. This employee has been reassigned pending an investigation."
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