But what awaits them on the outside of the doors are big and dangerous.
"When I'm parked, I usually keep an eye out and you see cars. When the bell rings, you see cars just going and sometimes they don't stop," says Andrea Torres Sosa.
Johnston Elementary is one of AISD's campuses that does not have a crossing guard to escort students onto and off the school's premises.
"It's a concern because you never know what's going to happen," says Sosa.
"I always have to tell them to stop because you never know when somebody's not even going to stop," another parent adds.
Which is exactly what happened Friday afternoon during our interview. A vehicle rolled straight thru the crosswalk showing no regard for the children waiting on the curb to cross.
"They need to slow down," says one student.
Her mother adds, "They were driving by too fast. I mean, at least have somebody to tell the kids it's alright to cross the street."
Which is why these parents want a crossing guard at this particular school, to make sure these close calls will be just that, close calls.
"They need at least somebody to help walk them because what we just saw, the car just zoomed past them and didn't even stop. It's just dangerous for the little kids."