Planets and Moons Teacher Guide

Unit

Planets and Moons

Subject

Earth and Space Science

Grade Level

ES 5-6

Activity Name(s)

Moon Phases

Seasons: Changing the Length of Daylight

Seasons: Changing Position of the Season

Being Prepared

Moon Phases

This activity can be done in partner groups or individually. If you need to work in partner groups, having the students take turns with doing the data collection on the computer and also making diagrams in their science notebooks will help keep both students involved. They can also compare their ideas looking at the recorded data in their notebooks and the computer recorded data. When doing the moon phases activity it is important to remind students that the moon is reflecting the sun's light so the sun is always part of the equation even though they don't see it in the model. The "Further Investigation" activity is very important as it helps tie the sun, earth, moon system together in the process of moon phases. To have them model the phases with the styrofoam having them form a circle before turning out the lights with the bulb in the center of the room will make things go smoother.

Hands-On Lab Materials

white 3-inch styrofoam balls (one per group)
strong light source (single bulb or goose-neck lamp)

Seasons: Changing Length of Daylight

Both this activity and the following activity are going to require managing a number of pieces of equipment to complete. Getting sensors and computers distributed and set up before starting to hand out other materials is important, especially if you're planning on doing the "Further Investigation" on the same day.

Hands-On Lab Materials

white 3-inch Styrofoam balls
pushpins (several colors)
marker
thin wooden skewer or wire coat hanger
point light source such as a bare bulb
surface temperature sensor (one per group)
black construction paper

Seasons: Changing Position of the Sun

In this activity managing materials is a consideration. Getting the styrofoam Earths set up before distributing the the computers and sensors will make management smoother. Also have the students practice with their model Earths, both rotating them to simulate a day and walking them in an orbit to show the revolution of the Earth around the sun.

Hands-On Lab Materials

light sensor
sensor interface
white 3-inch styrofoam balls
pipe cleaner
pushpins (several colors)
markers
3 x 5 file cards
swivel lamp
thin wooden skewer or wire coat hanger
earth globe
point light source such as bare bulb
temperature sensor (for "Further Investigation" activity)
black construction paper

Getting Started

Moon Phases

To run the models students need to first click the "SET UP" button and then push the "RUN" button to start the model. The "RUN" button also stops the model. When running the models it may be helpful for some students to use the slider at the top of the model to slow down the movement of the moon so they can track the moon's and Earth's location at the different phases. They should stop the model as they get to points where questions are posed in the activity. Encourage them to take snapshots and label them for each of the phases. For the "Further Investigation" you will need a darkened room, a bare light bulb and socket, and 3-inch white styrofoam balls. If you can get a hole drilled partially through the balls that is slightly smaller than a pencil, students can place the ball on their pencil to represent the moon with their head as the earth.

Seasons: Changing Length of Daylight

To run the models students need to first click the "SET UP" button and then push the "RUN" button to start the model. The "RUN" button also stops the model. They will need to change the latitude using a slider bar. Negative latitudes are in the Southern Hemisphere, 0 is the equator, and positive latitudes are in the Northern Hemisphere. Between each run they need to reset the model. In the "Further Investigation" section students will need to hook a temperature sensor. Make sure they understand the correct way to connect and disconnect the sensor from the computer. Make sure to closely supervise students as they are poking the "axis" through their model Earth.

Seasons: Changing Position of the Sun

In the "Further Investigation" section students will use a light sensor. Make sure they understand the correct way to connect and disconnect the sensor from the computer. When they are doing their data collection they will need to remember to keep the head of the sensor pointed at the paper attached to the styrofoam ball. Make sure to closely supervise students as they are poking the "axis" through their model Earth.

Suggested Timeline

The amount of time required to complete the 3 activities will vary depending on the number of computers available, whether you have the students work individually or in groups, and ability of the students. In general plan on 45 minutes to an hour to complete each of the 3 activities. The modeling parts of the lesson can be done as centers and then the "Further Investigations" can done whole group when students are done with the modeling section.

Thinking about the Discovery Questions

This unit is motivated by the discovery questions:

What causes the phases of the moon?
Why are there seasons?

When beginning to explore moon phases, it helps to start with an observational understanding of the changes before asking students to explain the phenomenon. Spending time having the students observe, draw, and record the phases at regular intervals will provide them with a foundation to understand the patterns involved. To build on this understanding, students can use the patterns to make predictions about the processes involved in the moon's phases. In addition, it is important to know that the phases are not caused by shadows and that the moon does not have a light and dark side.

What Students Need to Know

The ideas that "the sun is a star", and "Earth orbits the sun" are commonly misunderstood, even disbelieved, in the elementary grades. Explanations of the day/night cycle, phases of the moon, and the seasons are very challenging for students. To understand these phenomena, students should first master the concept of a spherical Earth. It will be equally important for them understand that the moon doesn't produce its own light; it reflects light from the sun. Finally, they will need some prior knowledge of the relative size and distances apart of the Sun/Earth/Moon system. For optimal participation in this activity set, students need to know these important things:

Earth is a sphere that orbits around the sun, making a full revolution in about 365 days
Earth is tilted on its axis (this needs to be modeled so students can visualize it)
The moon orbits Earth, making a full revolution every 28 days
The moon reflects light from the sun; it's not a light-emitting source

Misconceptions

Changing seasons and phases of the moon are phenomena that students regularly observe but often do not fully understand. Understanding that the earth is spherical is a precursor to comprehending other parts of the moon phase and season questions. Some students believe that the earth is a flat rectangle or a disc that supports the sky and the planets above it. Another roadblock to understanding these phenomena is the misconception that the sun moves around in the sky. Students in elementary school can have difficulty accepting that Earth orbits the sun because this runs counter to their experience as observers from the reference point of Earth's surface. Before students can comprehend moon phases they need to understand how light is reflected off a surface. In addition, understanding the that the moon is reflecting light (not producing its own) may make it difficult to connect the phases of the moon to their personal observations and the ideas they have developed. Within all of these questions is the need to understand relative size of the sun, earth, and moon and the relative motion of the three. Again this goes back to the students understanding that the earth is spherical.

Learning Objectives

NGSS

Performance Expectations
- 5-ESS1-2. Represent data in graphical displays to reveal patterns of daily changes in length and direction of shadows, day and night, and the seasonal appearance of some stars in the night sky.
- MS-ESS1-1. Develop and use a model of the Earth-sun-moon system to describe the cyclic patterns of lunar phases, eclipses of the sun and moon, and seasons.
Disciplinary Core Ideas
- Earth and the Solar System
  - Grade 5: ESS1.B.i 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.
  - Middle School: ESS1.B.ii This model of the solar system can explain eclipses of the sun and the moon. Earth's spin axis is fixed in direction over the short term but tilted relative to its orbit around the sun. The seasons are a result of that tilt.
- Electromagnetic Radiation
  - Grade 4: PS4.B.i An object can be seen when light reflected from its surface enters the eyes.
  - Middle School: PS4.B.i When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object's material and the frequency (color) of the light.
Practices
- Analyzing and Interpreting Data
  - Analyze and interpret data to provide evidence for phenomena.
- Constructing Explanations and Designing Solutions
  - Apply scientific ideas to construct an explanation for real-world phenomena, examples, or events.
- Developing and Using Models
  - Develop a model to predict and/or describe phenomena.
- Planning and Carrying Out Investigations
  - Collect data to produce data to serve as the basis for evidence to answer scientific questions or test design solutions under a range of conditions.
- Science and Engineering Practices
  - Science explanations describe the mechanisms for natural events.
Crosscutting Concepts
- Patterns
  - Similarities and differences in patterns can be used to sort, classify, communicate and analyze simple rates of change for natural phenomena.
  - Patterns can be used to identify cause and effect relationships.
  - Graphs, charts, and images can be used to identify patterns in data.
- Scale, Proportion, and Quantity
  - Time, space, and energy phenomena can be observed at various scales using models to study systems that are too large or too small.
- Scientific Knowledge Assumes an Order and Consistency in Natural Systems
  - Science assumes consistent patterns in natural systems.
  - Science assumes that objects and events in natural systems occur in consistent patterns that are understandable through measurement and observation.
- Systems and System Models
  - Models can be used to represent systems and their interactions.

NSES

Earth and Space Science — Earth in the solar system
- Most objects in the solar system are in regular and predictable motion. Those motions explain such phenomena as the day, the year, phases of the moon, and eclipses.
- 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 the sun's energy hitting the surface, due to the tilt of the earth's rotation on its axis and the length of the day.

Discussion: Setting the Stage

Moon Phases

What causes the phases of the moon?

The phases of the moon are caused by the relative positions of the sun, earth and moon over an approximately 28 day period. As the moon orbits the Earth, it is receiving and reflecting the Sun's light. Just like Earth, the moon is always half illuminated by the sun. But from our earthly reference point, and because the moon orbits Earth, we see varying fractions of the lighted segment of our moon.
Where does the light we see coming from the moon come from?

The moon is a solid chunk of rock with a dust surface. The light we see from the moon is reflected light from the sun. All the planets and their satellites (moons) reflect the suns light.
Why can we sometimes see the moon during the day?

The moon is the closest celestial body to the Earth, and that's why we can sometimes see if during daytime if conditions are right. For the moon to be visible during daylight hours, it needs to be overhead at the same time as the sun, but not too close to the sun. You can't see a full moon in daylight because it rises at sunset, is in the sky all night, and sets at sunrise. But you can see crescent, gibbous, and half moons if the Sun/Moon/Earth positions are just right.

Seasons

What are the four seasons we usually divide the year into?

Spring, Summer, WInter, and Fall
What are some differences you might notice in the Northern Hemisphere between the summer and the winter?

Summers have more daylight and the winters less. The summers are usually much hotter and the winters much colder.
Explain the relationship of the sun, earth, and moon to each other?

The sun is stationary in the center of our solar system. The Earth orbits the sun and the moon orbits the earth.

Discussion: Formative Questions

Earthmoonsystem-galileo

Moon Phases

As the model is running, where is the sun going to be in relationship to the sun?

The sun will be positioned so that the lit side of the moon is facing the sun, since that is the side that is reflecting the sun's light.
If you lived in the Southern Hemisphere and you saw a full moon today, what would someone in the Northern Hemisphere see today?

The phase of the moon is the same on the same day, no matter where you have viewing it from.

Seasons: Changing Length of Daylight

If you lived at the Equator what differences if any might you notice during the four seasons?

You might not notice any real difference. You would be getting the same amount of sun energy and sunlight year round so it would probably be pretty hot all the time.
What is the farthest north latitude you can set that will give you 24 hours without the sun setting in the Northern Hemisphere in the summer? Would this be the same in the Southern Hemisphere?

If you go to the Arctic Circle (a little past 66 degrees north) the sun would not set during the summer solstice and days immediately surrounding it. It would be similar in the Southern Hemisphere, you would just need to go a little past 66 degrees south.

Seasons: Changing Position of the Sun

Is the amount of light being reflected by the card different when you change the time of day on your earth?

Yes, as the ball is turned towards the sensor the amount of light being reflected directly will increase.
How does the amount of light energy being reflected relate to the temperature at different times of the day?

Earth temperatures are typically at their lowest daily points immediately before sunrise. As daylight progresses, light hits the Earth more directly and with greater intensity. This thermal radiation from the sun warms Earth all day as light energy is turned into heat, and the effect is cumulative. So on a sunny summer day the afternoon is usually the warmest.
How does the angle that the light is hitting the Earth affect the amount of hear energy that their might be?

The more direct the sunlight the greater the amount of heat that will be produced.

Discussion: Wrapping Up

Moon Phases

Do other objects in our Solar System have phases?

They do. One of the ones that can be easily seen with a telescope is Venus. Venus, like other objects, reflects the sun's light and we can see it going through it's phases. One way that Venus is different from our Moon is that when the Moon is full it is bright and dim when a crescent. Venus, on the other hand, is brightest when it is a crescent and dimmer when we would observe it as a full disk.
If the phase of the moon is the same on a particular day no matter where you observe it from, why can't an eclipse been seen everywhere you are on the planet?

Since the Sun, Earth, and Moon are all constantly in motion you have to be in the right place at the right time. A solar eclipse (when the moon moves between the sun and earth) may be seen over a large area, but the total eclipse will only be seen in 100 mile wide path.

Seasons: Changing Length of Daylight

Besides the North Pole, which experiences 24 hours of daylight between June, what part of the world would experience 24 hours of daylight in December? Explain.

The South Pole would experience 24 hours of daylight in December since, at that time, the Southern Hemisphere will be pointed toward the sun. This variation is caused by the tilt of Earth on its axis.

Seasons: Changing Position of the Sun

Alaska is close to the North Pole and they can grow really large cabbages. The number of growing days is short in the summer. Explain why the suns position makes this possible.

During the Alaskan summer, the sun's position relative to the Northern Hemisphere makes for very long days (up to 20+ hours). This means that the plants continue to grow without a "rest" period.
Since the Earth's orbit around the sun is a circle, but more like an oval, and the Northern Hemisphere's summer is when the Earth is just a little bit farther from the sun, why is it that our summers are still warmer even though we are farther from the sun?

It is true that the Earth is slightly farther from the sun during summertime for the Northern Hemisphere. But the extra Earth-to-sun distance is small compared to the "tilt" of the Earth's axis. It's the axial tilt that causes our season changes. Teachers: Expect this concept to be challenging to students. A widely-held misconception is that seasons change because Earth has a slightly oval-shaped orbit and it's hotter or colder depending on the distance from the sun. Why is this wrong? When Earth is at its perihelion (closest distance to the sun), it's 147 million km away. When Earth is at its aphelion (farthest distance from the sun), it's 152 million km away. This gives us a mathematical difference of only about 3%. But Earth's axis tilts 24.5%, which has a much greater effect. Why? Because sunlight can travel more directly to the part of Earth that is tilted toward it. Less sunlight is scattered and the surface will get hotter.

Additional Background

The connection between the sun, earth, and moon is a complicated one that we observe all the time but is frequently misunderstood. The earth is in motion around the sun in an elliptical orbit that takes about 365 days (a year) to complete. The elliptical nature of this movement helps control our seasonal cycles. At the same time the earth is rotating on its axis at a slight tilt.

The moon also rotates as it is going around the Earth. A lunar day (one rotation) is the same as a lunar month, about 28 earth days, so the same side of the moon is always facing the Earth.

Analysis

Moon Phases

Newmoon

When the moon is between Earth and the Sun, is the moon full or is it dark?

Answer: Dark or a new moon. We can't see the lit section of the moon. (See image above.) Teachers: This is an area of great misconception among students. Ask them to remember that the moon is not a light-producing object -- it reflects light from the sun. Have them stop the model when the full moon phase is showing (just as in the image above). Remind them that in this model, sunlight is coming from the RIGHT side of the image. If they look closely, they can see that the sun's light is all being reflected away from Earth. The moon is still there....we just can't see it.

Fullmoon

When Earth is between the moon and the Sun, is the moon full or is it dark?

The moon is full. The entire lit section is visible. Teachers: This is a great time to integrate a discussion of using models to explain science phenomena. Remind students that in this model, the sun is always supposed to be to the RIGHT side of the Earth/Moon system. If we can imagine a big sun over on the right of the model, it's easier to understand what's happening. In the model, the sunlight shows on the Earth as blue and on our moon as white. There will be nothing blocking the moon's reflection of sunlight. That's why they see a full moon.
Does the moon change shape as it waxes and wanes?

The shape of the moon stays the same. The amount of the lit section that is visible from Earth changes.
Does the moon make its own light, or does it reflect the Sun's light? Explain.

The moon does not make it's own light. It's a ball of rock and will reflect light from the sun, but doesn't produce it's own.
A solar eclipse is when the moon blocks the Sun's light by being exactly between the Sun and Earth. At what phase of the moon does this happen?

It can only happen if there is a new moon.
A lunar eclipse is when Earth blocks the Sun's light from falling on the moon. At what phase of the moon does this happen?

It can only happen if there is a full moon.

Seasons: Changing Position of the Sun

At what latitudes does the Sun stay almost directly overhead at noon for most of the seasons?

0 degrees.
At what latitudes is the Sun sometimes close to the horizon, even at noon?

The closer you get to the North or South Poles, you can experience the phenomenon of the sun rising very little above the horizon in winter months. This occurs in December-February in the Northern Hemisphere and June-August in the Southern Hemisphere. It can be observed from about 60 degrees to 90 degrees, North and South latitudes.
For which latitude is there the greatest change in sunlight energy from summer to winter?

At 90 degrees North (North Pole) and at 90 degrees South (South Pole). This is due to the Earth's axial tilt. The two poles experience the greatest amount of tilt, and thus the greatest change in daylight/night patterns. The poles remain cool (even in summer) because they are never tilted in a direct path of sunlight -- lots of light is scattered by the atmosphere before it reaches the surface of the poles.
For which latitude is there the smallest change in sunlight energy from summer to winter?

At 0 degrees (the equator), the Earth's tilt has the least effect. Equatorial regions experience very little change in day/night patterns because each day of the year the sun strikes at the same angle.
How does Earth's tilt create summer and winter? Explain how this changes the position of the Sun.

During the summer the Earth is tilted more directly towards the sun. In the winter the Earth is tilted away from the sun. The hemisphere that is tilted toward the sun is warmer because sunlight can travel more directly to the surface with less scattering in the atmosphere.

Seasons: Changing Length of Daylight

Why does the length of the day change less near the equator than near the poles?

At the equator there is little change in day/night patterns because it doesn't experience the effect of the axial tilt. Each day the sun strikes the equator at the same angle. Every day of the year, the equator receives about 12 hours of sunlight.

Sydneysummer Losangeleswinter

Sydneywinter Losangelessummer

2. Why is it summer in Australia when it is winter in the USA?

(See images directly above) Be sure students pay attention to the white line in the model that represents Earth's axis. The four images above show Sydney, Australia and Los Angeles at both winter and summer solstices. Each city is at about 34 degrees latitude -- Sydney at 34 S and Los Angeles at 34 N. Because of the tilt of the earth and the fact that it revolves around the sun, at the point in the earth's revolution that the Southern Hemisphere is pointed more directly to towards the sun (far left image), the Northern Hemisphere is pointed away from the sun. This results in the Southern Hemisphere having summer and the Northern Hemisphere having winter.

3. Is the Sun always directly overhead at the equator, all year? Explain.

No. It will only be directly over head at the 2 equinoxes, March and September 21. The length of day stays the same though year round.

4. There is a tilt angle in the model when every location on Earth has equal day and night. This is called the spring or fall equinox, depending on the preceding season. What is the tilt angle at the equinox? Experiment with the model to find out.

At 0 degrees. Remember that this is relationship to the Earth's position to the sun.

5. There is a latitude where in summer the sun never sets, and in winter the sun never rises. What is that latitude? Experiment with the model to find out.

North of 72 degrees or so up to 90 degrees the sun never sets (drops below the horizon) in the summer or rises (comes above the horizon) in the winter. The same is true for the Southern Hemisphere at 72-90 degrees South.

Further Investigation

Moon Phases

After students have completed the activities in moon phases, another investigation that will help reinforce what they have done would be to keep observational logs of moon patterns for an extended period of time. The logs could be sent home with the goal of having students try to make an observation each day this is possible. If done for a 2-month period the patterns students discovered in the models should become apparent in their moon logs. Teachers: Since moonrise often occurs after kids' bedtimes, you might make use of internet tools for tracking moon phases. Try moonconnection.com for a calendar that lets you set month, year, and hemisphere. It will provide a photo that closely approximates the shape of the moon for a target date.