An introduction to cognitive research literature—particularly studies which appear in teacher journals—sheds light on the ability of students of various ages to understand many of the topics in Science for All Americans and Benchmarks for Science Literacy. This component also includes Benchmarks’ Chapter 15: The Research Base and its accompanying bibliography of more than 300 references. Curriculum developers can use this component as a guide to data on student learning of specific topics and teachers can use it to help make decisions about instruction and materials.