Helping your child out with their homework is always a humbling experience, as one dad recently learned firsthand. Gary, an Alabama-based dad with a first grader, recently took to Reddit to crowdsource some help with his son’s take-home assignment, sharing that the missing-word exercise had “stumped” him “entirely.”

Gary shared a screenshot of the paper given to his son at school, which included 10 fill-in-the-blank sentences, each missing a word. Though all 10 words were included to help assist students, Gary found himself stumped by two of the 10 responses.

The responses in question: “What’s the [blank] of the pen?” and “Our [blank] has white stars.”

Inexplicably, the prompt included the words “mass” and “fist,” which didn’t seem to line up with either of these options. Most commenters who responded noted that there was likely an error when printing the word banks, since “flag” was not included as a potential answer. Others agreed that “mass,” which was included, made sense for the pen question, although Gary rightfully wondered what a first-grader would know about physics.

Some noted that first-graders might actually understand the concept of mass. “Mass is pretty reasonable for a first grader to know; most first graders can even tell you their own mass,” they wrote. “First graders understand that the more stuff you have, the more it’s gonna weigh. They also understand that in space, things are weightless. … And I also think it makes sense to talk about when they learn about gravity, which is definitely a first grade topic. They also might know many other words related to mass, such as massive (huge; containing a lot of stuff).”

Others pointed out additional head-scratching issues with the assignment, including the sentence that swaps “fewer” for “less” in “There are [blank] boys than girls.”

For his part, Gary explained why he took to the internet for some assistance. “I posted asking for help because we had no clue what the correct answers could be,” he told Newsweek. “It’s been decades since we were in first grade and maybe there was something we could have missed.”

“Those that offered their thoughts came to the same conclusion as we did, that there was an error with the worksheet,” he added. “It was a relief to know I wasn’t just dumb. There [was] no obvious answer except that it was an error.”

Of course, we’ve all felt silly when trying to help a kid with their homework only to realize we’ve got no idea what we’re doing. But sometimes, it really is the simplest answer—a formatting or printing error—and it’s never a bad idea to get a gut-check from others when you need one. Here’s hoping the rest of his assignments are far more straightforward, both for Gary and his son.