Amidst the COVID-19 pandemic, education systems globally implemented protective measures, notably mandatory mask-wearing. As the pandemic's dynamics changed, many municipalities lifted these mandates, warranting a critical examination of these policy changes’ implications. This study examines the effects of lifting mask mandates on COVID-19 transmission with-in Massachusetts school districts. We first replicated previous research that utilized a difference-in-difference (DID) model in COVID-19 incidence. We then repeated the DID analysis by replacing the outcome measurement with the reproductive number (Rt), reflecting the transmissibility. Due to the data availability, the Rt we estimated only measures the with-in school transmission. We found a similar result in the replication using incidence with an average treatment effect on treated (ATT) of 39.1 (95% CI: 20.4 to 57.4) COVID-19 cases per 1,000 students associated with lifting masking mandates. However, when replacing the outcome measurement to Rt, our findings suggest that no significant association between lifting mask mandates and reduced Rt (ATT: 0.04, 95% CI: -0.09 to 0.18), except for the first two weeks post-intervention. Moreover, we estimated Rt below one 4 weeks before lifting mask mandates across all school types, suggesting non-sustainable transmission before the implementation. Our reanalysis suggested no evidence of lifting mask mandates in schools impacted the COVID-19 transmissibility in long-term. Our study highlights the importance of examining the transmissibility outcome when evaluating interventions against transmission.