Background: Evidence indicates that tailored educational resources such as e-Bug in schools can improve students’ knowledge of infection prevention. This study aimed to (1) understand the feasibility of using soap use data as a proxy for measuring student handwashing behaviours and (2) refine a study method that could be implemented by local authorities and schools to assess impact as a result of the implementation of e-Bug. Design: A stepped-wedge design was employed, and 10 primary schools were randomly assigned to groups where teachers were trained to use e-Bug, either in July 2019 (early intervention group) or in January 2020 (late intervention group). Pre/post student knowledge-retention questionnaire data and soap use measurements were collected from all schools before and after the early group teachers used e-Bug. The sample included 16 soap use measures, 561 students in the early group and 601 students in the late group. Statistical analysis involved single/multivariable mixed-effects linear and logistic regression. Setting: A local authority in England. Results: In 15–18 questions, there was a significant relationship between training and students answering questions about microbes, hand/respiratory hygiene and antibiotic use/resistance correctly (degree of change varied). There was not enough power to comment on the relationship between the intervention and soap use. Conclusion: This study informs the feasibility of cluster, randomised, controlled trials in educational settings to measure the impact of educational resources. It can be used to inform future studies and highlights the need to ensure adequate sample size to estimate soap use and improve the measurement accuracy of data collection tools.