"My grandmother taught me to do good in school, to focus and listen to my teachers," she told kids at an assembly in the courtyard before classes started.
She later told us she hopes her appearance will have a lasting impact throughout the year.
LIST: Bay Area back-to-school dates
"I just remember when I was in elementary school and when people visited my school who were famous, I would get super excited. Also, my teachers would say something like 'Didn't Ronnie Lott tell you to listen?', the Mayor said.
Some parents were emotional as they faced the beginning of a new year.
"I cried this morning because my baby is in the 5th grade. She is growing up," said Marnisha Price, who also recognized the benefits of sending the kids off for the day.
"I am happy because I am going to have groceries in my house because she ate me out of house and home this summer," Price said, laughing.
Caroleen Fang wiped away tears as she watched her daughter walk in to start her year as a kindergartener.
"I am excited for her. This is a new chapter for her and for us," Fang said.
The Mayor also had a serious focus as the year gets underway: keeping kids safe as they head to and from school.
"We want to make sure people are aware there are kids who are out there going to school walking and biking and taking MUNI- be careful slow down," Mayor Breed said.
She has a list of different initiatives she plans to put into place out on the streets.
"Number one pushing for a lot more enforcement and making sure we are addressing those high accident areas, injury corridors where we know there are significant problems," she said.
The Mayor also said new infrastructure and more crossing guards will be part of the plan to keep kids safe.