describes the fundamental idea that underlie the standard. Content is fundamental if it

• Represents a central event or phenomenon in the natural world.

• Represents a central scientific idea and organizing principle.

• Has rich explanatory power.

• Guides fruitful investigations.

• Applies to situations and contexts common to everyday experiences.

• Can be linked to meaningful learning experiences.

• Is developmentally appropriate for students at the grade level specified.

Three criteria influence the selection of science content. The first is an obligation to the domain of science. The subject matter in the physical, life, and earth and space science standards is central to science education and must be accurate. The presentation in national standards also must accommodate the needs of many individuals who will implement the standards in school science programs. The standards represent science