Seeing the Light
Exploring the Sun's Role in the Living Systems

Students create webs that illustrate their thinking about seasonal physical and biological changes caused by changes in sunlight. They begin to grasp the central role of sunlight in living systems.

1 period and ongoing additions to chart

chart paper, markers


Most students have learned that sunlight makes plants grow, some animals eat plants, and predators eat other animals. However, they may not have thought about how these food chains and webs change with the seasons. For example, during spring in the Northern Hemisphere, lengthening and strengthening sunlight and rising temperatures boost plant photosynthesis, which increases the amount of food they produce.

Laying the Groundwork
Ask small groups of students to make a list of five changes they think the sun will bring about as winter wraps up and spring springs forth in their community. Suggest they think of both physical changes (e.g., temperatures) and biological changes (e.g., plant growth). Have the class create a master list of these changes along with questions they have.


1. Ask students to review their list and discuss what kinds of impact each physical change (e.g., ice melting, more daylight hours, temperatures warming) might have on living things — particularly on their ability to make or get food. Consider introducing or reviewing the concept of food chains. You might, for instance, ask, What do plants need to grow and thrive (e.g., sun, warmth, water)? As they grow, what does it mean for animals that depend on plants? For animals that eat other animals?

2. As the class discusses ideas, use a large piece of paper to begin to create a Web to illustrate them; use the sun as a starting or center point (see the example, right). Help students explore connections between sunlight and changes in living things as spring emerges.

3. As spring progresses, read updates from Journey North and keep a running list of new connections students discover between sunlight and spring events. Have them use another marker color to add these to their Web. How can their findings help answer some of their initial questions? What new ones do they have?

Making Connections

1. Where and how would you fit animal migration into our web?

2. Did any of the new connections we made during the season surprise you? Why?

3. How do seasonal changes in photoperiod (daylength) and the sun's intensity affect your animal's food web?

Note the new connections students make and add these to the class web over the course of their migration studies.

National Science Education Standards

Science as Inquiry
Use data to conduct a reasonable explanation. (K-4)

Develop descriptions, explanations, predictions, and models using evidence. (5-8)

Life Science
All animals depend on plants. Some animals eat plants for food. Others eat animals that eat plants. (K-4)

For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs. (5-8)

Earth and Space Science
The sun provides light and heat necessary to maintain the temperature of the earth. (K-4)

The sun is the major source of energy for phenomena on the earth's surface, such as growth of plants, winds, ocean currents, and the water cycle. Seasons result from variations in the amount of sun's energy hitting the surface, due to the tilt of the earth's rotation on its axis and the length of the day. (5-8)

Sunlight webbing example