concepts, principles, and even other theories in the discipline. Each guides new research and can be understood in progressively more complicated ways. Each enables creative links to be made between disciplines. For example, atomic-molecular analyses are important in physics, chemistry, biology, and geology. Biologists work with DNA molecules to understand patterns in genetic code and unravel the interrelations of species. Chemists seek to articulate the laws that govern interactions between molecules that result in newly formed or broken chemical bonds. And teams of multidisciplinary experts—including chemists and biologists—draw heavily on molecular science to develop drugs that attack unhealthy molecules (or cells) and leave others undisturbed.

The proposed use of core concepts and learning progressions still requires significant additional research and development on the part of science educators, scientists, and education researchers. The science education community will need to identify core ideas, and specific learning progressions will need to be developed and tested extensively in classrooms.

Here we define learning progressions and offer an example of how learning progressions might be structured over the course of the K-8 school years. This is a dramatic departure from current classroom practice. Many educators and school systems are not in a position to pursue an immediate wholesale change to their science curricula. Accordingly, later in the chapter we reflect on the incremental steps that can be made right away at the classroom and the school levels.

Organizing science education around core concepts that provide a specific context for learning is a significant departure from typical classroom practice. Science educators must work cooperatively to define long-term goals for students that take into account the reality that students need opportunities to learn over multiple years to deepen their understanding of scientific concepts. Much thought will need to be given to how specific experiences along the K-8 grade span will accumulate and contribute to student learning and how to provide the kinds of support that teachers will need to accomplish this.