BALTIMORE (WJZ) — An Anne Arundel Community College teacher says he learned a valuable lesson about being specific on his first test day of the semester.

Reb Beatty, who teaches business administration at the school, says he typically allows a “3×5 notecard” for students to use as a cheat sheet during exams.

READ MORE: Inside The Case: How Federal Agents Built Their Investigation Into Catherine Pugh's 'Healthy Holly' Book Scandal

“Today, a student shows up with this,” Beatty wrote on Facebook caption of a student with a jumbo-sized test guide.

“Sure enough, it is 3×5… feet. As precise as I am, apparently I never specified inches and therefore yes, it was allowed. Well played and lesson learned for me.”

READ MORE: 3 Dead In Domestic-Related Laurel Shooting, Child Hospitalized

His post has been shared more than 20,000 times and liked more than 24,000 times since he shared it on Tuesday.

MORE NEWS: Police Continue To Investigate Woodlawn Shooter's Background, Neighbors Say They Have Been Complaining For Years

Follow @CBSBaltimore on Twitter and like WJZ-TV | CBS Baltimore on Facebook