We’re sure all die-hard Harry Potter fans think they’ve noticed just about every detail about the book series and movies- or at least have tried to over the years. As far as the films go, there are definitely new things to see every time you watch, including minor things you might not even regard as intentional. For example, has anyone noticed that after Harry Potter and the Chamber of Secrets, the students at Hogwarts almost abandon their robes altogether and begin dressing like everyday Muggles? Well, that was on purpose.

In the first two films, wearing the Hogwarts uniform is considered very important, as the kids are seen with their robes on at nearly all times. But in Harry Potter and the Prisoner of Azkaban, the students hardly ever wear them outside of the classroom. This is because costume designer Jany Temime, who worked on the last six films, was brought on for the third and had a different vision for the kids.

“I thought that they should look normal, that they should look like normal kids,” Temime explained to InStyle. “I wanted a real feel. I wanted to make Harry Potter not a little story that you read in bed but something real. Because at the end of the day, they are teenagers coming from dysfunctional families, all of them, and then living together in a boarding school and all those kids have special gifts.”

The third film is also when the students begin to mature a bit, so it would make sense they’d grow tired of their childhood robes and want to dress for themselves. So yes, they did dress like Muggles, but they also dressed like the teenagers they were.

Every Harry Potter detail has a purpose, no matter how small or insignificant it seems.

This article also appears on Mental Floss.