# Rotation and Revolution of the Moon: Active Model

By Laura Hospitál on Feb 16, 2016

As I was contemplating how to describe why we only view one side of the Moon, this simple model came to my mind.  Students work in groups of two to model the motion of the Moon around the Earth and the rotation of the Moon.

Note:  If an APH globe is not available, I have listed an easy way to adapt this activity in the variations section.

## Preparation:

• Blow up a balloon for each group to about 1/4 the diameter of the globe.
• Place a tactile marker on one side of the balloon.

## Procedure

1. The student representing the Earth should stand in a fairly open part of the classroom.
2. Describe the Moon to the students.  Tell them that the side of the Moon that faces Earth does not change and that this activity will help them understand why.  The balloon represents the Moon and the tactile marker represents the side of the Moon facing the Earth.
3. Have the Moon student face the appropriate side toward the Earth.  Ask the Moon student to think about which cardinal direction he is facing in the classroom (or alternatively toward which object in the classroom he is facing.) This will be important later.
4. As the Moon revolves around the Sun, guide the student to keep the same side of the Moon toward the Earth.  (Though the Earth is of course rotating at the same time, it may be easier just to remind the students that this is occuring, but not to physically rotate the Earth for this activity, as it may confuse the main point of the lesson.)
5. Say:  "The reason that the same side of the Moon always faces the Earth is that the Moon rotates on its axis in the same period of time (27.3 days) that is revolves around the Earth.
6. As the student who is playing the Moon reaches his original location, ask him to think about which direction he is facing in the classroom. (It should be the same as when he started. This is because the Moon rotated once on its axis in the same time that it revolved around the Earth.)
7. Repeat this activity with the other student as the Moon.

## Variations

• This activity could be done with one student as the Moon and a stationary Earth if only one student is participating.
• Also, rather than a model of the Earth and the Moon, the students could themselves represent the Earth and the Moon.  In this case, have the "Moon" face the Earth and as the Moon rotates, have the student always face the Earth.

## NGSS Standards:

#### Grade 1 - Space Systems, Patterns and Cycles

ESS1.A: The Universe and its Stars
Patterns of the motion of the Sun, Moon, and stars in the sky can be observed, described, and predicted. (1-ESS1-1)

#### Grade 5 - Space Systems, Stars and Solar Systems

ESS1.B: Earth and the Solar System

The orbits of Earth around the Sun and of the Moon around Earth, together with the rotation of Earth about an axis between its North and South poles, cause observable patterns. These include day and night; daily changes in the length and direction of shadows; and different positions of the Sun, Moon, and stars at different times of the day, month, and year. (5-ESS1-2)

#### Middle School - Space Systems

ESS1.A: The Universe and Its Stars
Patterns of the apparent motion of the Sun, the Moon, and stars in the sky can be observed, described, predicted, and explained with models. (MS-ESS1-1)