gogical content knowledge when they know the specific ideas students are likely to bring to the classroom (such as the idea that plants get their food from the soil), the ideas most likely to be difficult (such as how ATP-ADP transformations occur), and how to best deal with these difficult concepts using examples, analogies, models, and demonstrations (Hashweh, 1987). In Joanna’s case, her experiences with inquiry learning and teaching are building her pedagogical content knowledge. Her understanding and abilities of inquiry were sharpened in the museum program where she learned to ask good questions and design investigations to gather evidence she could use to explain
the observations that piqued her interest. As she engages her own students in inquiry, she has become conscious of how they learn to ask questions about scientific phenomena and how she can help them do so. She observes how they combine their developing language skills with use of their bodies. She is learning what materials stimulate her children and help them develop explanations of light and color. She has arranged the learning environment to reflect all of the essential features of classroom inquiry.
Joanna’s professional development program emphasized her experiences with inquiry and focused less on how she could bring these into her classroom. Other kinds of professional development programs focus more directly on inquiry-based teaching. They help teachers think in new ways about what they want their students to learn, how they can help them learn it, and how they will know whether and what students have learned. They focus more directly on strengthening teachers’ pedagogical content knowledge in science.
Preservice or graduate courses and in-service workshops are still the most prevalent formats for teachers to develop and improve their inquiry teaching. But many other strategies also are being used throughout the country to help both prospective and practicing teachers learn more about teaching science through inquiry. Loucks-Horsley et al. (1998) have identified 15 different strategies for professional development, including case discussions, examining student