The objective of the MealSim study is to empower school nutrition directors with evidence-based strategies specific to their institution to improve student fruit and vegetable consumption while decreasing food waste through the development and evaluation of a school meal systems agent-based model simulation tool. The project aims to improve fruit and vegetable consumption and reduce food waste. Research activities are being conducted through two key objectives: 1) Build an agent-based model (MealSim) to simulate dietary behavior in school meal systems and 2) Validate MealSim using data from school nutrition programs in collaboration with key stakeholders. Year 4 centered around the training for and execution of new plate waste data collection in 12 schools located in Baltimore, MD (n=3), Chicago, IL (n=3), Madison, WI (n=3), and Rockbridge County, VA (n=3). These data will be used to validate MealSim. Staff and student research assistants from several universities and community partners, led by Case Western Reserve University, Johns Hopkins School of Public Health, and World Wildlife Fund, were trained on the research protocol and general plate waste data collection methodologies. One pilot audit was held in each school, and 4 rounds of data collection were completed at each school, consisting of structured observations of the cafeteria environment, student time use estimation, and plate waste measurement. The methodologies used for data collection reflect changes, such as more nuanced time use data, requested by key stakeholders, and the use of data collected from schools in multiple states will improve the generalizability of the agent-based model. It is anticipated that MealSim will empower school nutrition stakeholders to make evidence-based decisions on how to modify their cafeteria operations to improve fruit and vegetable consumption and reduce food waste, ultimately resulting in improved public health and environmental sustainability. [ABSTRACT FROM AUTHOR]