Many young children, at one time or another, have asked for a jar, run outside, caught an animal to bring home, and sat watching it for hours. Others have helped plant seeds or gardens and become fascinated as they see plants spring into life.

Children have a natural curiosity about both animals and plants. But few have been asked to look at the two together, to think about how plants and animals are alike and different, and to think about themselves as organisms, too.

Organisms, a 16-lesson unit designed for first-graders, gives children the opportunity to explore these likenesses and differences and thereby, to become more aware of the diversity of life. As they investigate a variety of organisms, students discover that organisms have certain basic needs, such as food and water. In addition, they learn that organisms have certain specific needs--needs specific to the type of organism--such as type of water, range of temperature, and type of food. In observing and taking care of a number of different plants and animals, students begin to develop positive attitudes and a sensitivity toward living things.

At this age, children are developing their observation skills. Using more than one sense, they are moving from focusing on one characteristic to focusing on several characteristics at a time. They are beginning to use direct comparisons to identify similarities and differences among objects. In addition, first-graders are starting to classify objects and to give reasons for their classifications.

Children are also developing the ability to relate their concrete experiences, not only through drawing and speaking but also through the written word. Increasingly able to focus on people and things outside themselves, they are starting to listen more to what others have to say and to work more effectively in groups.

The first lesson gets students thinking about what living things need to live and be healthy and about the ways all plants and animals are alike and different. A pre-unit assessment lesson, it provides you with a sense of students' present thinking about the unit's central themes.

Lessons 2 and 3 introduce students to the first organism they will study: plants they grow from seeds. Students create an observing table, a tool that helps them sharpen their observation skills. Throughout the unit, children consult and add to this table. This activity encourages them to use more than one sense as they observe their different organisms.

Moving from how a seed grows into a plant to how plants flourish in their natural homes, student groups set up woodland terraria with moss and young conifer trees in Lesson 4 and freshwater aquaria with Elodea and Cabomba in Lesson 5. Establishing the process they will use throughout the unit, students observe, record, discuss, and compare features of the two woodland plants and then the two freshwater plants.

In Lesson 6, students return to the seeds they have planted, observed, and cared for over a period of time. Here, for the first time, they focus on growth and change in an organism, discuss what plants need to live, and create their own readers that capture their experiences about growing plants from seeds.

To expand the class's understanding of the diversity of life, Lessons 7 through 10 introduce four animals: freshwater snails and guppies for the aquaria, and pill bugs and Bess beetles (or millipedes) for the terraria. By adding these animals to the two environments, students begin to notice not only that plants coexist with animals but also that animals coexist with other animals. This time, students observe, record, discuss, and use Venn diagrams to compare the two woodland animals and then the two freshwater animals. In addition, by observing a pair of guppies (male and female), they discover that similarities and differences exist within the same kind of organism.

Lessons 11 and 12 reinforce the class's emerging awareness that living things grow and change. Students observe, discuss, and write about changes that have occurred in the terraria and aquaria over time.

Lessons 13 through 15 help students move from the specific to the general, forming their own ideas about the ways plants and animals are alike and different. Using Venn diagrams, students first explore how all their plants are alike and different; then, how all their animals are alike and different; and finally, how all eight of these plants and animals are alike and different. To enhance their understanding of these concepts, in Lesson 13, students read about four unusual plants from around the world. And, to reinforce their awareness of organisms' basic and specific needs, the class reads about how a zoo prepares a home for a new organism, a crocodile.

In Lesson 16, students are ready to apply what they have learned about organisms to the one organism in the classroom they have not yet discussed: themselves. How are we like other organisms? How are we different? Through drawings and words, students compare themselves with other living things.

This is an exciting unit for young students. They get to observe, touch, hold, and care for a number of living things that have been chosen especially for their strikingly different characteristics and that exemplify the variety that exists in nature. By bringing a part of the natural world into the classroom, you give children a deeper understanding of the diversity of life. And you help them see that all living things are like one another in many ways but are also unique unto themselves.