Officials say the teacher wanted to teach the student a lesson on behaving in class.
The incident happened at Lake Shore Elementary School in a second grade classroom.
The teacher said, "if you don't sit down, I'm going to tape you to your seat."
The child allegedly said OK and the teacher did exactly that.
RELATED: Teacher fired after physically kicking student out of class
Although this incident was not recorded, it didn't take long for the news to reach the principal's office.
By then, it was anything but a laughing matter.
WBAL-TV reported that in a letter to parents, the principal wrote, "I was shocked and appalled upon hearing about this incident. Our school is a place where every child is embraced, loved and nurtured."
The school district is also taking it seriously.
The head of the county's teachers' association said, "We hope this can be used as a learning experience for us to ensure that substitutes are properly prepared for the challenges of the classroom."
Police say the teacher is not expected to face any charges.