This dataset consists of two files – one main dataset, and one dataset for the re-test analysis. The main dataset includes an anonymous participant ID, binary responses to 30 environmental knowledge questions, participant's sex, age and duration to complete the task. The re-test dataset includes all the same variables, completed for both the initial study and at re-test after nine weeks. When collecting this dataset, we were seeking to develop a new measure of environmental knowledge, building upon an existing measure by Geiger et al. (2019).