Key Idea 1:

Living things are both similar to and different from each other and from nonliving things.

There are basic characteristics, needs, and functions common to all living things. Nonliving things are present in nature or are made by living things.

Younger studentsí ideas about the characteristics of organisms develop from their basic concepts of living and non-living things. As students are given opportunities to observe and classify living and nonliving things, they should be reminded that living and nonliving things are sometimes given attributes they do not really have. Understanding the variety and complexity of life and its processes can help students develop respect for their own

and for all life. It should also lead them to better realize the value of all life on this fragile planet.

Key Idea 2:

Organisms inherit genetic information in a variety of ways that result in continuity of structure and function between parents and offspring.

As students investigate the continuity of life, emphasis should be placed on how plants and animals reproduce their own kind.

Teachers should lead students to make observations about how the offspring of familiar animals compare to one another and to their parents. Students know that animals reproduce their own kind ?rabbits have rabbits (but you can

usually tell one baby from another), cats have kittens that have different markings (but cats never have puppies),and so forth. This idea should be strengthened by a large number of examples, both plant and animal, upon which the students can draw. Students should move from describing individuals directly (e.g., she has blue eyes) to naming traits and classifying individuals with respect to those traits (e.g., eye color: blue). Students can be encouraged to keep lists of things that animals and plants get from their parents, things that they don ít get, and things that the students are not sure about either way.

Key Idea 3:

Individual organisms and species change over time. Throughout time, plants and animals have changed depending on their environment.

In learning how organisms have been successful in their habitats, students should observe and record information about plants and animals. They should begin to recognize how differences among individuals within a species can help an organism or population to survive. Students at this level will identify the behaviors and physical adaptations that allow organisms to survive in their environment.

Key Idea 4:

The continuity of life is sustained through reproduction and development.

It is essential for organisms to produce offspring so that their species will continue. Patterns of reproduction, growth, and development of an organism are stages in its life cycle. Life cycle stages are sequential and occur throughout the life span of the organism. The characteristics of the cycle of life vary from organism to organism.

Note: Younger students may have difficulty in recognizing the continuity of life. Using organisms with a short life cycle as examples will be important in getting the concept across. It is important for younger students to observe

life cycle changes in selected animals.

Key Idea 5:

Organisms maintain a dynamic equilibrium that sustains life. Students need many opportunities to observe a variety of organisms for the patterns of similarities and differences of the life functions used to sustain life. All organisms carry out basic life functions in order to sustain life. These life functions include growing, taking in nutrients, breathing, reproducing, and eliminating waste. Students need many opportunities to observe and compare these similarities and differences in a variety of organisms. Specimens that could provide these opportunities may include guppies, mealworms, and gerbils, as well as fish, insects, mammals, birds, amphibians, reptiles, plants, and fungi.

Key Idea 6:

Plants and animals depend on each other and their physical environment.

Plants and animals interact in a number of ways that affect their survival. The survival of plants and animals varies, in response to their particular environment. As the physical environment changes over time, plants and animals change.

Younger students should focus on simple, observable associations of organisms with their environments. Their studies of interactions among organisms within an environment should start with relationships they can directly observe.

Key Idea 7:

Human decisions and activities have had a profound impact on the physical and living environments. Humans are dependent upon and have an impact on their environment. Students should recognize how human decisions cause environmental changes to occur.

Students should be given opportunities to identify and investigate the factors that positively or negatively affect the physical environment and its resources.