1. Ask students to share their ideas about the Moon. Encourage them to talk about what they have already observed and any conceptions that they may have. Ask:

1. What does the Moon look like? Does it always look the same?
2. When do you see it?
3. In which part of the sky do you see it?
4. What do you think the Moon is made of?
5. Why do you think the Moon has phases?

2. Explain that the class is going to study the Moon based on their own observations. Ask:

1. What does it mean to make observations?
2. How can we make observations of the Moon?

3. Show the first minute of the Galileo: Discovering Jupiter's Moons, which discusses some of Galileo's observations of the Moon.

1. What did Galileo observe about the Moon?
2. When you look at the Moon without a telescope, what does its surface look like?

4. (Optional) Discuss what the Moon looks like up close. Remind students that humans have actually been on the Moon and have taken pictures and brought back samples of Moon rocks. Work though the Explore the Moon as a class.

5. As a class, look at the Phases of the Moon to see examples of how the Moon can appear from Earth. Discuss each screen as you go through the interactive.

6. Explain that the class will be making daily observations of the Moon and recording them in a Moon Journal. Their journal entries will include sketches of how the Moon looks each day (when visible), as well as the date, time, location of the Moon in the sky (direction and height above the horizon), weather conditions, and the name of the phase.

7. Distribute the notebooks for the Moon Journals. Have students make their first journal entry as a class. If the Moon is in first quarter, it should be visible during the afternoon. Go outside as a class and help students locate the Moon. Note: Remind students never to look directly at the Sun.

8. Assign students to continue to make daily observations of the Moon in their journals.

9. After a few days of observations, have students look at their journal entries. Ask:

1. How has the appearance of the Moon changed?
2. Does the Moon always appear to be in the same place? Does it always rise in the same direction? Does it move across the sky?
3. How does the Moon's position change from day to day?
4. Can you predict what the Moon will look like and where in the sky it will be at a given time tomorrow?

10. After a couple of weeks of observations (past the full phase), have students look at their journal entries again. Ask:

1. What pattern do you notice in the Moon's changing appearance?
2. Can you predict what the Moon will look like tomorrow? In a week? In a month?
3. When do you think it will be in the new phase again?
4. What do you notice about the curve of the visible part of the Moon?
5. What do you think is causing the changes in the Moon's appearance?

11. Explain that the Moon does not give off any light of its own -- it only reflects sunlight. Because the Moon revolves around Earth, it looks different to us from day to day as it changes position in its orbit. For more information about how the Moon orbits Earth, show the Why Doesn't the Moon Fall Down?. Note: Even though Earth is sometimes positioned between the Sun and the Moon (such as at full moon), it is much smaller than the Sun, so it doesn't usually block the Sun's rays from reaching the Moon. However, occasionally, the three bodies line up just right so that Earth does block sunlight from reaching the Moon, causing a lunar eclipse.

12. Distribute the balls and have students work in pairs to model the Earth-Moon-Sun system. The light source, representing the Sun, should be placed in a central area with the students surrounding it. Each student represents Earth, and the ball (held at arm's length) represents the Moon. Half of the ball should be illuminated, and as the student rotates in place, the visible portion of the illuminated part will mimic the phases of the Moon. Have students explore this model for a few minutes. Note: To an observer on Earth, the curved side of the lit part of the Moon always faces the Sun (notice how it changes side before and after the new moon phase).

13. Review the phases of the Moon: new, crescent, quarter, gibbous, and full. Write the names of the phases on the board and also have students draw an illustration on the board of each phase.

14. Choose a phase and point to its illustration. Ask students to position their Moons so that they look like the picture. For example, if you ask for a full moon, the students need to manipulate their positions to simulate the full moon phase (i.e., the lamp is behind them and the fully lit side of the Moon is facing them). Have students explain the following:

1. What portion of the Moon is illuminated?
2. How much of the illuminated portion do you see?
3. Does the Moon itself actually change shape?

15. Have students challenge their partners with the model -- one student acts as the model while the other asks for specific phases. Make sure each student has a chance to be both the model and the challenger. Then ask:

1. What did this model demonstrate?
2. What did you learn about how the Sun, Moon, and Earth move in relation to one another?
3. How many times does the Moon travel around Earth to complete a full cycle of phases?

16. (Optional) Show The Origin of the Moon. This video segment from NOVA follows the Apollo 15 astronauts as they collect samples of ancient rock from the Moon's crust. The discovery of this ancient rock helps lead to a radical new theory about the Moon's origin. Note that this video segment is intended for middle school and high school students.