Study timeline and procedures
The optimization phase of the study was conducted between October 2017 and March 2020. The study was designed to occur over a 10-month period, which included teacher training, baseline assessments, classroom observations, and implementation of the 27-week food literacy curriculum. The four candidate components were implemented over 11 weeks beginning in January of each year. Child assessments were conducted at baseline (∼November), mid-intervention (∼January/February), post-intervention (∼March/April), and at 3-month follow-up (∼June). Physical and sedentary activity were the only measures collected at mid-intervention, on days that the active play curriculum was implemented. Teachers and parents completed web-based or paper-and-pencil surveys at baseline and post-intervention. Research staff and Penn State University Extension educators conducted two coaching sessions for the core food literacy curriculum, and two sessions per experimental curriculum assigned (0–6 visits), which were used to increase implementation fidelity. As such, these research staff were not blinded to experimental condition. During coaching visits, the classroom environment was observed, including teachers’ interactions with children and use of classroom materials.