The Nine Concepts
According to the U.S. Department of Education, there are nine basic concepts that every elementary and middle school child should know. We've listed them here, along with some questions about the Chesapeake Bay to help you and your children start thinking about these concepts in context.

• Classification
Scientists use organization and classification to sort through the variety of objects and phenomena in the natural world.
- Can you name ways blue crabs and oysters are the same?
- Can you name some ways they are different?

• Cause and Effect
Nature is filled with rules and laws that shape our world. Discovering these laws is at the root of science.
- What happens when too many nutrients fill the Chesapeake
  Bay?

• Systems
A system is a group of smaller units that combine and work together in an orderly way to form a larger unit known as a whole.
- An estuary is a special system. How do its fresh water and
  the salt water work together to create a habitat suited for
  fish, shellfish, and other creatures?

• Scale
Objects and energy vary in quantity. Scales, such as thermometers, are used to measure and compare those variations.
- What are some things a scientist might measure with a
  scale in the Chesapeake Bay?

• Models
A model is a representation of a thing or phenomenon. Models can transform a difficult concept into a hands-on learning experience.
- Imagine you are making a model of the Chesapeake Bay.
  What are some things that you might include?

• Change
Everything in nature experiences change.
- The Bay changes with the seasons. List some changes that you might expect to occur in the Bay between summer and winter.

• Structure and Function
The way an object is made often relates to the function it performs. The study of this relationship is a fundamental part of science.
- Can you describe an animal in the Bay whose special body
  helps it to survive?

• Variation
Many things in nature share similar properties, but all organisms have distinct properties that make them unique.
- Fish, oysters, and crabs all live underwater. Can you name
  some things they have in common? Can you name some
  ways in which they are different?

• Diversity
It takes many different parts to make a system work. The study of diversity helps children understand and see the ways the systems of the world are connected.
- Can you name some of the plants and animals that work
  together to form the Chesapeake Bay's ecosystem? What
  would happen if the Bay only contained one kind of plant?