The computational model of school achievement represents a novel approach to theorizing school achievement, conceptualizing educational interventions as modifications to students' learning curves. By modeling the process and products of educational achievement simultaneously, this tool addresses several unresolved questions in educational psychology through computational modeling. For example, prior research has highlighted perplexing inconsistencies in the relationship between time spent on task and academic achievement. The present simulation reveals that even under the assumption that time-on-task always positively contributes to achievement, the correlations between time-on-task and achievement can vary substantially across different contexts and, in some cases, may even be negative. Analysis of the correlation between prior knowledge and knowledge gains uncovers similar patterns. The computational model of school achievement presents a framework, bolstered through simulation, enabling researchers to formalize their assumptions, address ongoing debates, and design tailored interventions that consider both the school environment and individual student contexts.