Why do men dominate the fields of science, engineering, and mathematics? Should there be single-sex schooling? What is intelligence? How do people learn? Always evident in her writing about thought and knowledge, cognitive psychologist Diane F. Halpern’s answers to apparently straightforward questions like these are far from simple, yet they are clear. Halpern’s research has yielded many principles of learning, such as the importance of formative assessment to learning, and she has designed and implemented programs for — among other areas — undergraduate education in psychology, critical thinking, spatial thinking, and even automated tutoring. She has argued against single-sex schooling, noting the weak empirical evidence for the benefits of such segregation as well as the potential for negative impacts like institutionalized sexism. In addition to gender differences, Halpern studies other aspects of cognition, including intelligence and critical thinking.