My mom is a janitor.
That's cool. Where does she work? Janitors work in hospitals, schools and residential accomidations. 
She works at a high school.
Janitor
A janitor (American English, Scottish English), custodian, porter, cleaner or caretaker is a person who cleans and maintains buildings such as hospitals, schools, and residential accommodation. Janitors' primary responsibility is as a cleaner. In some cases, they will also carry out maintenance and security duties. A similar position, but usually with more managerial duties and not including cleaning, is occupied by building superintendents in the United States (and occasionally in Canada) and School Site Managers in schools in the United Kingdom
List of janitors
A janitor (American English), (Scottish English) janitress (female), custodian "cleaner" or caretaker is a person who cleans and maintains buildings such as hospitals, schools and residential accommodation. Janitors' primary responsibility is as a cleaner. In some cases they will also carry out maintenance and security duties.
This is a list of notable people who have been janitors.
Australia.
- Frank Jenner (often misspelled Genor; 1903–1977), evangelist
Cuba.
- Adela