* Self-taught: Calpurnia, being a strong and independent woman, likely taught herself to read. She was the housekeeper and a caregiver to Jem and Scout, so she probably had ample opportunity to practice.
* Informal education: Calpurnia may have learned to read from other Black people in Maycomb, through informal classes or shared literacy practices.
* Formal education: Though unlikely given the limited access to education for Black people in the South during that era, it's possible Calpurnia attended a school for African Americans.
It's important to remember that Lee leaves some aspects of Calpurnia's background vague, allowing readers to interpret her character and her literacy in their own way. However, her ability to read is a testament to her intelligence, resourcefulness, and resilience in a society that limited opportunities for Black people.