Our star, the Sun, is an ordinary star. It is not particularly special compared to other stars in the universe; however, it is crucially important to us. As the massive energy source at the center of our solar system, the Sun is responsible for Earth's climate, weather, and life. In this lesson, students use observations, activities, and videos to learn basic facts about the Sun. Students also model the mechanics of day and night and use solar energy to make a tasty treat.
- Know that the Sun appears to move in predictable patterns (every day it rises in the east and sets in the west, and its position in the sky changes throughout the seasons)
- Understand that the Sun is a star and that its radiation both lights and heats Earth.
- Understand that night and day are a result of Earth's rotation
- Recognize that all the planets in our solar system orbit the Sun
Grade Levels: K-2, 3-5
Three class periods
A few minutes each day throughout the year (optional)
- Observe Sunrise and Sunset QuickTime Video
- Galileo: Sun-Centered System QuickTime Video
- Characteristics of the Sun QuickTime Video
- Cooking Cookies with Solar Power QuickTime Video
- 1 directional compass
- 1 calendar (optional)
- 1 lamp with exposed light bulb
- 1 extension cord
- Styrofoam balls -- one for each student
- Small sticker dots -- two for each student
- Pencils to mount Styrofoam balls -- one for each student
- For each solar cooker:
- 2 large sheets of poster board, preferably black
- 1 sheet of black construction paper
- 1 medium-sized cardboard box
- aluminum foil
- For each student's s'more:
- 2 graham crackers
- 1 large marshmallow
- 1 chocolate square
- 1 re-sealable plastic sandwich bag
Before the Lesson
Set up and try the model Earth demonstration to make sure that the lighting in the classroom will be effective. The light source should be placed in a central location with room for students to stand around it.
Mount all the Styrofoam balls on pencils — pierce the balls such that the pencil can act as an axis of rotation.
Familiarize yourself with the Characteristics of the Sun QuickTime Video.
Build and try a solar cooker to approximate the length of time it will take to cook the s'mores.
Place a marshmallow and a graham cracker in a plastic bag for each student.
Part I: Observations of the Sun
1. Ask students to share what they know about the Sun. Record on the board their responses to the following questions:
- Why is the Sun important?
- What is the Sun made of? How big is it? Where is it?
- What causes day and night?
2. Show the Observe Sunrise and Sunset QuickTime Video. Ask:
- What did the video show?
- Have you ever seen a sunrise or a sunset? What did it look like?
- Does the day begin at sunrise or at sunset? Does it end at sunrise or at sunset? How do you know?
3. Discuss the different ways that people experience sunrise or sunset. For example, in some locations, people observe the Sun rise and set over land or water. In other locations, people observe the Sun rise and set behind tall buildings. Ask:
- Which windows in your home get sunlight in the morning? In the afternoon?
- Does the Sun always rise and set at the same time each day? (Before students answer, have them think about how early it gets dark in the winter versus how late it gets dark in the summer.)
4. Have students use a compass to determine the direction of the Sun in the sky. If the Sun is shining through windows in the classroom, this activity may be done indoors. If there is no sunlight in the classroom, have students go outdoors. Record the time and direction of the Sun at hourly intervals to track the Sun's movement throughout the day. (Note: Remind students that they should never look directly at the Sun.) In the meantime, ask:
- Have you ever watched sunlight coming in through a window? How does it change throughout the day?
- When is the Sun highest in the sky?
- Does the Sun appear to move the same way every day?
5. (Optional) To see how the Sun's position in the sky changes over the course of a year, have students judge the height of the Sun at the same time each day. By quickly glancing in the direction of the Sun, they should be able to categorize its position as low, medium, or high. Record the Sun's position on a calendar -- students should observe that the Sun is lower in the sky in winter and higher in summer. Note: Remind students that they should never look directly at the Sun.
Part II: Earth's Rotation and Revolution
6. Ask students to think about why the Sun appears to move through the sky the way that it does. Explain that some of the greatest thinkers in history had disagreements over whether the Sun orbits Earth or whether the Sun is still and Earth rotates.
7. For grades 3-5, show the Galileo: Sun-Centered System QuickTime Video. (K-2 teachers may want to view the video for background information.) Then discuss the following:
- The ancient Greek astronomer Ptolemy thought that Earth was the center of the solar system. How does this theory explain day and night?
- Copernicus thought that it made more sense that everything orbited the Sun. How does this theory explain day and night?
- Why did people think that the Sun-centered theory was an impossible theory?
- Galileo was the scientist who found convincing evidence for the Sun-centered theory. What evidence did he see?
8. We now know that Earth (along with all the other planets in our solar system) orbits the Sun and that day and night are a result of Earth's rotation. Distribute the foam balls and stickers to have students model day and night -- do not worry about accurately modeling the tilt of Earth's axis. The light source, representing the Sun, should be placed in a central area with the students surrounding it. Have students place a sticker somewhere on their foam ball (the ball represents Earth and the sticker represents a place on Earth). As they rotate the ball (Earth spinning on its axis), they will see that sometimes the sticker is on the light side of the ball (daytime) and sometimes it is on the dark side (nighttime).
To show why the Sun appears to rise in the east and set in the west, have students place a second sticker to the left of the first sticker. Tell them to label the first sticker "E" for east and the second sticker "W" for west. Then have them rotate the balls counterclockwise (as viewed from above). Which dot receives light first?
Part III: Energy from the Sun
9. Show the Characteristics of the Sun QuickTime Video once, all the way through. Replay the video and pause for discussion at important facts: The Sun is made of superheated gas; it is the center of our solar system; it is smaller than an average star, yet more than one million Earths could fit inside its volume; it has a temperature of about 3 million degrees Fahrenheit; it is about 93 million miles away from Earth. Students should be able to answer the following questions:
- What is the Sun composed of?
- What does it mean to say that the Sun is the center of our solar system?
- If the Sun is so hot, why doesn't Earth melt?
- If the Sun is a star, why does it look so different from the stars we see at night?
10. Discuss how we receive energy from the Sun in the form of light and the importance of the Sun for life on Earth. Ask:
- What does sunlight feel like?
- How does the Sun affect your life? How does it affect plants? Animals?
- What would Earth be like without the Sun?
11. Have students make a solar oven to harness the energy in sunlight. Break the class into groups of four and distribute the materials. Explain that they are going to use the Sun to cook s'mores. Discuss the following questions:
- What does an oven do? What do you think a solar oven does?
- How do you think our solar ovens will work?
- Where does the solar oven get its energy from?
- What are the properties of each of these materials: poster board, black construction paper, aluminum foil, cardboard, plastic bags, and marshmallows? How will sunlight interact with them?
12. Show the Cooking Cookies with Solar Power QuickTime Video to demonstrate what they will be building - a cone-shaped solar cooker. Lead students through the assembly instructions, as follows:
- Tape the two pieces of poster board together to form one long piece.
- Cover one side of the poster board with aluminum foil.
- Bend the poster board into a loose cone shape, with the foil side facing in. There should be a large opening at one end of the cone and a smaller opening at the other end. Tape the poster board in place.
- Place the black construction paper on the bottom of a cardboard box.
- Place the cone in the box, with the smaller opening resting on the construction paper.
- Place the baggies with the marshmallows and graham crackers inside the cone.
- Place the solar cookers in sunlight for an hour or two.
- When the marshmallows are gooey, have students retrieve their baggies.
- Distribute the chocolate squares and more graham crackers. They may now finish building their s'mores and enjoy the effects of the Sun's energy!
Check for Understanding
- Have students draw four pictures of the same outdoor scene with hills and trees; they should leave the sky empty (no Sun). Have them (or help them) write east on the right side and west on the left side of each picture. In the first picture, tell them to fill in the sky like it's sunrise (Sun on east side, sunrise colors). The second should show noon (Sun overhead, blue sky). The third should show sunset (Sun on west side, sunset colors). The fourth picture should show night (no Sun, sky colored dark, stars and moon optional).
- Have students draw a picture about how the Sun affects people, plants, and animals.
- Have students discuss these vocabulary words: Sun, Earth, stars, day, night, sunrise, sunset, rotate, solar system, year.
- Have students design and build different types of solar ovens. Compare and analyze the ovens for efficiency.
- Have students discuss applications for solar energy.
- Have students write a response to the following question: If you lived on the coast of California (on the mainland of America's West coast), would you see the Sun rise or set over the Pacific Ocean? Why?
The Digital Library for Earth System Education (www.dlese.org) offers access to additional resources on this topic.