James Trefil is the Clarence J. Robinson Professor of Physics at George Mason University and chief science consultant for the McDougal Littell Science Series.

With science education, it's a classic good news/bad news situation.

The good news is that scientists agree on what everyone is supposed to know. The bad news is that we're not doing as good a job of teaching it as we could be.

Sometimes giving a student a simple way to organize information is the most important part of teaching a subject. This is especially true in the sciences, where students can sometimes be overwhelmed by seemingly unconnected concepts. However, it turns out there is an easy way to do this. There is a hierarchy embedded in the fabric of science that we call the Big Ideas approach. In using this approach, you can quickly arrive at an intellectual organizational structure that not only makes sense scientifically, but also provides a useful framework for teaching.

Here's a useful analogy that will help you understand the Big Ideas approach: Imagine that all of the phenomena of the world are arranged around the edge of a large spider web. You might have stars here, trees there, and butterflies somewhere else. Start anywhere on that edge and start asking questions: What is this? How does it work? What does it mean? Do this, and you will find that the answers bring you toward the center of the web. Along the way, things that seemed very different from each other are seen to be connected by the Big Ideas. Trees and butterflies, for example, use the same genetic code to run the chemical reactions needed to sustain life.

Keep this process up long enough and you come to the very center of the web. Here you find the grand principles that govern the physical universe—the Big Ideas. These are the overarching laws that work their way out through the spider web to explain everything we know about the physical universe.

Examples of these Big Ideas are the conservation of energy—the idea that energy can be neither created nor destroyed, but cycles endlessly through the universe—and evolution by natural selection. These ideas are the skeleton—the lifeblood—of science.

It makes no difference what part of the universe a scientist studies—whether it is the ecology of a tropical lake, the chemical origin of life, or an exploding supernova in a distant galaxy. He or she will use this principle as part of any explanation of how that particular phenomenon works, regardless of how different the various phenomena might seem. The Big Ideas, then, form a kind of intellectual framework on which all scientific knowledge can be hung. As such, they constitute a splendid base for science education. No matter what subject is under discussion, from global warming to stem cell research, the scientific basis for the debate will always come back to the Big Ideas.

To my knowledge, I was the first to develop a science education program based on the Big Ideas while at George Mason University in the mid 1980s. Since then, the concept has been put into practice in approximately 200 universities and colleges around the country, and is now being applied to middle school textbook programs.

In the end, when I think about the Big Ideas approach to science education, I come down to this: We may not know what great social issues will be debated twenty years from now because of new advances in science. Certainly no one twenty years ago would have predicted that we would be talking about stem cells and cloning today. But the one thing I can predict with absolute certainty is that whatever those future issues are, they will be firmly grounded in the Big Ideas. Today's students face an increasingly complex scientific world, while schools require greater accountability for their understanding of these concepts. What better reason to ensure that our students are supplied with an essential intellectual scaffolding, the strategy of Big Ideas in science?