Federal Loan forgiveness programs require you to work full time. If you are pursuing Teacher Loan Forgiveness (TLF), this disqualifies you from the program.
However, if you are pursuing Public Service Loan Forgiveness (PSLF) and you work part time for two eligible employers (at the same time), and the part time hours from both add up to more than 30 hours/week, you can still pursue PSLF.
See this related article regarding Qualifying Employment: https://bysavi.zendesk.com/hc/en-us/articles/360060787353-What-does-Qualifying-Employment-mean-in-terms-of-loan-forgiveness-TLF-PSLF