12-year-old Caitlin Theriault of Auburn, Maine's Park Avenue Elementary School wanted to write about her two moms for a class essay. The assignment was to come up with persuasive topics that the whole class could write on.

But when Caitlin's pitch — why having two moms can be great — wasn't included on a list for students to choose from, she and her parents wanted to know why.

"We were disappointed, at that point in the school, but then in the teacher," mom Erica Ackley told Portland's WMTW. "We've come a long way as a society, but being at school, we should not have to feel that that's not OK. School should be a safe space."

Yet according to Katy Grondin, superintendent of the district, the decision wasn't meant to be an exclusionary one.

"There was absolutely no intent by the teacher to discriminate," Grondin said. "The topic was supposed to be broad enough for the whole class to write about."

Other pitches left off the list included more sports-focused topics, like steroid usage in professional athletics.

Caitlin's apparently been moved to another English class since. She'll reportedly be allowed to write the essay when the assignment is more personal.

"We all have different backgrounds and different lifestyles," Grondin said. "And we honor those."

Watch WMTW's full report here: