Bertha is a female bus driver who drives buses for Third Street School. She has appeared in multiple episodes, even being part of the main storyline on one occasion.
She drives a yellow school bus that she has nicknamed "Old Smokey", which is seen taking the children on a field trip in "Operation Field Trip". In the episode, the school bus breaks down on a count of it being really old and used which upsets Bertha greatly. The kids, lead by Gretchen and Spinelli, use parts that are laying around to fix the broken down bus which is seen to be working better than ever.