We investigated the intersectional relationships between racism, sexism, and classism in inequities in student conceptual knowledge in introductory biology courses using a quantitative critical framework. Using Bayesian hierarchical linear models, we examined students' conceptual knowledge as measured by the Introductory Molecular and Cell Biology Assessment. The data came from the LASSO Platform database and included 6547 students from 87 introductory courses at 11 institutions. The model indicated that students with marginalized identities by race, gender, and class tended to start with lower scores than continuing-generation, White men. We conceptualized these differences as educational debts society owed these students due to racism, sexism, and classism. Instruction added to these educational debts for most marginalized groups, with the largest increases for students with multiple marginalized identities. After instruction, society owed Black and Hispanic, first-generation women an educational debt equal to 60-80% of the average learning in the courses. These courses almost all (85/87) used collaborative learning and half (45/87) supported instruction with near-peer learning assistants. While research shows collaborative learning better serves students than lecture-based instruction, these results indicate it adds to educational debts due to racism, sexism, and classism in introductory college biology courses.