A fifth-grade teacher in Hyrum, Utah was fired last month for showing his students postcards of famous works of art, a few of them featuring nudes. The teacher at Lincoln Elementary School, Mateo Rueda, a visual artist and native Colombian, first moved to the area to study art at Utah State University.

Rueda told Salt Lake City’s Fox13 that he found the postcards, part of Phaidon’s Art Box set of 100 cards, in the school’s library. He decided to use them to teach a lesson about color theory, but he didn’t realize the eight boxes of postcards contained works that some students (and their parents) might deem inappropriate or offensive.

When students started snickering at Amedeo Modigliani’s “Iris Tree” (1916), François Boucher’s “Brown Odalisque” (1745), and Jean Auguste Dominique Ingres’s “The Valpinçon Bather” (1808), Rueda says he explained that the paintings were an important part of history. One of his students told Fox13 that her teacher said if they felt uncomfortable with certain paintings, they could take the cards back up to him and just look at the rest — including Leonardo da Vinci’s Mona Lisa and Vincent van Gogh’s “Sunflowers.”

A parent of one of Rueda’s students found out about the “incident,” going so far as to call the police and report the teacher for exposing children to “pornography.” (Who knows how they might have reacted had the class been studying modern art and getting into the work of Georgia O’Keeffe.) Rueda says the postcards were school property, so there’s no reason to blame him personally for bringing them into the classroom.

Fortunately, there were no charges filed against the teacher, but Rueda is still out of a job. A slew of letters have been sent to the editor of Logan, Utah’s Herald Journal newspaper in the teacher’s defense. Rueda told the newspaper that he is appealing his termination, but whether or not the school district takes him back remains to be seen.