of all groups and ages in formal and informal settings. Fundamental researchgenerates knowledge and understanding with the potential for broad relevance. The potential implications of ECR fundamental research for improving STEM education practice may be indirect and long-term rather than direct and immediate. Moreover, whether they include basic or use-inspired basic research, all successful ECR:Core proposals focus on the advancement or refinement of foundational knowledge for STEM education. The amount of funding and duration requested in proposals submitted to the ECR:Core solicitation should align with the maturity of the proposed work and the size and scope of the empirical effort. The solicitation has three levels of funding with a range of budget sizes, and proposals may request a duration of 3 to 5 years for any level: (1)Level I proposals may request up to $500,000; (2)Level II proposals may request up to $1,500,000; (3)Level III proposalsmay request up to $2,500,000. All proposals should justify the level of funding and duration in the project description.