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Unit Plan |
Moon Phases:
The Role of Light, Cycles and Illusions
Laura Sylvan
Graham and Parks School
Cambridge, MA |
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AGI, TERC, and their employees do not warrant the completeness, accuracy, appropriateness,
and/or safety of the procedures, materials, and content contained herein.
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Stage 1: Identify Desired Results |
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Unit Description |
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"O swear not by the moon, the inconsistent moon,
That monthly changes in her circled orb,
Lest thy love prove likewise variable..."
William Shakespeare
Romeo and Juliet
From Romeo and Juliet to more modern times, people have witnessed the monthly cycle of moon phases. What is difficult to understand are all the factors at play that create the changing face of the moon.
This unit is developed around having students separate out these factors : light's role in what we see, the movement of the moon and earth in relation to the sun (or cycles) and that often what we see in space are apparent shapes (termed illusions). As students use models and direct observations to study moon phases they will focus in on these 3 factors and the interplay between them. Another important idea in this unit is for students to look at misconceptions that have developed around moon phases |
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Relationship to the Big Ideas in Earth Science: |
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20.The relative position and movements of the earth, moon, and sun account for lunar and solar eclipses, the observed moon phases, tides and seasons.
21. Earth scientists use representations and models, such as contour maps and satellite images to help them understand the Earth.
22. Scientists use quantitative and qualitative, experimental and non-experimental methods of scientific inquiry to understand the Earth. |
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Unit Enduring Understandings: |
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- The nature of light allows us to "see" something.
- Cycles in the movement of the earth, moon, and sun create repeating patterns of what we observe on earth.
- The intangible aspects of objects out in space lead to many illusions about the size, shape and movement of these objects. Models allow scientists to manipulate these intangibles and understand what causes the illusions.
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Unit Essential Questions: |
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- What causes the lit surface of the moon to appear to change its shape?
- How does the shape of a moon phase relate to when it is visible in the sky?
- What makes a solar eclipse so rare? Why don't we see one every new moon?
- How do models help and hinder our understanding of moon phases?
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What students will need to know and be able to do (knowledge and skills): |
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- We are able to see something when light is emitted or reflected off an object into our eyes. An object appears "dark" if less light reflects from an object and into our eyes. A shadow forms when light is blocked by an opaque object.
- The moon and earth cycle through a revolution and rotation. Earth's revolution around the sun in 365 days makes up one year. The 24 rotation makes up one day. The moon's revolution and rotation are the same and take roughly 28 days. Time intervals used by humans are roughly based on these cycles.
- The phases of the moon are created by the relative position of the moon to the Earth and the Sun.These phases each have names.
- Eclipses form when the moon's shadows fall on the Earth or the Earth's shadow falls on the moon. These do not occur often due to the scale of the earth and moon to the sun and a slight tilt to the moon's orbit.
- To effectively use an astronomical model you need to take into account the scale and perspective for the model.
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What do students typically misunderstand? |
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- The dark portion of the moon is caused by the Earth's shadow or clouds.
- Different countries can see different phases of the Moon on the same day.
-The Moon makes light the same way the Sun does
- The Moon goes around the Earth in a single day.
- The Moon is always out in the night sky (it may be blocked by clouds or buildings).
- The Sun, Moon and Earth are about the same size and fairly close together in space. |
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Stage 2: Determine Acceptable Evidence |
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What is the Goal of the performance? |
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Students will identify 5 mistakes or misunderstandings about moon phases found in a mock "student moon journal". They will also explain what the corrects ideas are that tie in to each mistake or misunderstanding and make 1 or 2 proposals for helping students correct their ideas. |
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What Role does the student assume in the performance? |
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A science researcher interested in student's misconceptions in astronomy. |
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What Audience does the student address? |
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A fellow science researcher conducting similar research |
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What is the Situation for the performance? |
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As a researcher you are sharing ancedotes about what today's students might be thinking about moon phases. You are looking through student work to locate specific examples. You are beginning to brainstorm some ideas on how to help correct their thinking about certain misunderstandings or common mistakes. |
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What Product should be produced? |
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A memo of your findings from reading through this particular moon journal. The memo clearly states the 5 misconceptions or mistakes and explains what the correct ideas are for each of them. With the memo are suggestions about how scientists and teachers could help students with their thinking that causes such mistakes and misunderstandings. |
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What are the Standards for the product? |
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-Students correctly identify 5 misconceptions/mistakes found in student journal
- Correct explanations given for each 5 misconceptions or mistakes
- Creative and thoughtful suggestions made for helping students to better understand these ideas.
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Preconception Survey: |
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Quizzes, Tests, and Academic Prompts: |
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Misconception Quiz (pre and post) and Self Evaluation/ Reflection Questions: - How do 3-D models work for helping you understanding the phases of the moon? What is confusing about them? - Why do science illustrators use out of scale drawings so often in their textbooks? -We know the sun and moon are not the same size, but they seem to be during a solar eclipse, how is that? -What would appear different about the moon if it rotated twice during each revolution? - Is the moon the only object in space that goes through phases? - If the moon was a cube, how would the phases of the moon look? |
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Other Evidence: |
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Moon Calender Student Observations during Moon Modeling activity |
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Stage 3: Plan Learning Experiences, Instruction, and Resources |
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Use WHERETO as a guide to describe the learning experiences, instructional strategies, and resources you will use to help students
address the essential questions of the unit and achieve deep understanding of the big ideas. |
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WHERE: Discuss outline of the unit. Share enduring understandings, and essential questions. Go over final product. Introduce the use of the daily journal for reflections and self evaluations throughout the unit. Give the pre test on misconceptions (if not given earlier).
Pre Test Questions (True or False) are:
1. The Moon spins.
2. There is a side of the Moon that never receives sunlight and is always in darkness.
3. You see the Moon because it scatters light from the Sun towards you.
4. The moon changes phase when it passes through the Earth's shadow.
5. The Moon takes 1 day to orbit around the Earth.
6. If the Moon is directly overhead at 10 pm tonight, it will be directly overhead at 11 pm tomorrow night.
7. The Moon changes phase when clouds or planets block our view of part of the Moon.
8. The Moon is the only object in space that has phases.
9. When people in Washington, D.C., see a crescent Moon at night, people in Hawaii will see a full Moon later the same evening.
10. The moon is always out at night but might be blocked by buildings or clouds so we cannot see it.
HOOK: Set up a light source that shining on a sphere and discuss with students what the light is doing in order for them to "see" these objects. Bring out the ideas of emitted and reflected light. Look for shadows and discuss what causes them. Also discuss what makes some parts of the sphere appear dark.
Hand out photographs of objects in space ( Venus in the crescent phase, an eclipse, a phase of the moon, Earthrise over the moon) As you look at these photos consider what is causing the bright lit areas and what causes the dark areas. Students need to think about the direction of the light source for any reflected light areas. Have students fill in worksheet and be prepared to discuss their ideas.
EXPERIENCES & EXPLORATIONS:
1. Demonstration showing that half the moon is always lit as it circles the earth. Why do we see it differently (tie this in to illusions)? Ask students to create different phases using the sun as a light source, a sphere (orange) and themselves as the earth. Give students a worksheet of the sphere photographed in different phases and ask them to create the same phase using the sphere. Have them record the angle to the sun needed to create each phase? (Prompt: Is he moon the only object in space that has phases?)
2. Hold a discussion on how the different angles created the phases. Emphasize the idea of where light was reflecting of the sphere and where there were unlit areas. Give the names for the phases of the moon. Also discuss the question of different objects having phases. What would be necessary for that to happen? You can show students several websites on the phases of Venus and discuss what is happening with the lit vs. unlit areas. How are the phases of Venus like and not like those of the moon? photos of Venus' phases Galileo's drawings of Venus' phases diagram of Venus' phases
3. One more way to emphasis the role of reflected light to create phases is to ask students the Prompt: What would the moon's phases look like if the moon were a cube? Allow students time to discuss and draw their ideas for several of the phases. Then using a light source and a small wooden cube ask students to test out their ideas.
4. Moon Modeling Activity using DELTA Scientific models. Work through lessons that clarify the ideas of revolution and rotation for the earth and moon. Look at what happens astronomically in terms of a day, a year, a month, a week. Go through phases of the moon with these models. (Prompt Question: How often will you experience these different cycles in your life: year, month, day, week,solar eclipse, lunar eclipse?)
5. Emphasize the frame of reference being used as they observe the phases of the moon. Is what they see from the viewpoint of someone above the solar system, someone on earth, someone near the sun? What would each of these people see? A website that does a good job toggling back and forth between two views is this one:2 Views of Moon Phases
6. Work out a model of why only one face of the moon is ever visible? Walk through a revolution and rotation. Discuss the difference between the dark side and the far side of the moon.(Prompt question: What would appear different about the moon if it rotated twice during each revolution? If it never rotated? Also have students comment on the scientific accuracy of Mark Twain's quote: "Everyone is a moon, and has a dark side which he never shows to anybody.")
7. Have students work on a month long Moon Journal. This should be started early in the unit. After some initial comments on how to best make observations, students can work on their own with some check- ins through out the classtime. A good way to start this unit is to go outside with students and review where East and West are, the path of the sun, the horizon, etc. Make use of STARRY NIGHT astronomy program to get some extra observations done for those cloudly nights. Make sure students are considering not only the shape, but when and where the moon was observed. (The moon Phase Clock is useful to make with students to help them think about MoonRise and MoonSet times)
If possible, go through two months of cycles on one Moon Journal. Have students record the next full moon on the same page as the other one. Did they see it in the same location or at the same time or same date the next month?
8. Lesson on where shadows lie based on direction of light source. A good on line lab about locating an object based on the shadows lies at http://www.learner.org/teacherslab. The idea of complete and partial shadows can also be developed from this.
9. Demonstration using a light source, small ball and globe for students to consider the location of the shadows of the moon and earth as they move in space. Bring out the vocabulary of solar and lunar eclipses. (Prompt question: Why don't we get an eclipse evey new and full moon ?)
10. Possible reading from PROJECT SPICA about photons and light.
11. Do Scale Model Lab from PROJECT STAR book. Afterwards discuss or demonstrate the challenge of getting the shadow to fall on the earth or moon for eclipse conditions. Also use this acitivity to discuss/demonstrate the illusion of the moon and sun being the same size in the sky and during an solar eclipse.
Note: If students are interested in how people know the actual size or distance betwen the sun, moon and earth there are several labs (Estimating Size and Distance) in PROJECT STAR to followup on this.
12. Look at drawings in a text book of lunar phases and of eclipses. Discuss the use of scaling with these graphics. (Prompt Question: Why do textbook illustrators choose to use poor scaling? What are the trade offs for doing this?)
13. A good visualization of the moon orbit tilt is on the STARRY NIGHT atronomy program by clicking on the ecliptic and located the moon against it in the program. Students should notice the tilt above and below this line as they look at a month's worth of cycles.
14. Do a reading on Benjamin Bannekar. How did he make his observations? Why was knowing these cycles important earlier in history?
15. Consider the path of the moon's orbit in the sky. If we could freeze the Earth's rotation, how would we see the moon move across the sky? How could we freeze the rotation in a way? By going to the same time each night and observing the moon we can get a sense of this. Use the STARRY NIGHT program and allow students to try this.
REFLECT: Students will keep a daily journal that they write entries in at the start or end of class. The Prompt questions that are placed throughout Experiences will be recorded here. There should be a short Reflection question each day that asks students to tie in their ideas about light, cycles and illusions (models too) to what they are learning or a picture or image they are shown.
Another good resources to use for reflections in the book Concept Cartoons from pgs 175-184 with drawings about the moon.
EVALUATIONS:
1. Practice toggling between earth view and space view by showing students the site : http://www.astro.wisc.edu/~dolan/java/MoonPhase.html. This allows them to see one view and then switch over to the other. Do this as an all class activity or individually. Can they look at one view and accurately draw the other?
2. Questions from PROJECT STAR book- pgs 152-154 and Pg. 150.
3. Look at web sites (yet to be determined) to look at mistakes and misconceptions seen there. Explain what they are and what needs to be done to correct them. (Bad Astronomy)
4. Take misconceptions test again and go over changes in their thinking.
5. Complete the final GRASPS task.
6. Take a Lab Practical . Questions would include the following:
a. From photos of objects in space, label where emitted and reflected light is. For any reflected light, state the direction of light source.
b. Shown a view of a moon phase correctly show the placement of earth, moon, sun to create this phase. Consider the time of day in Cambridge to this view.
c. Given the Earth-Moon-Sun drawings, state the correct view seen from Earth (and when it would be seen)
d. Use model to make predictions of changes in the moon's position and shape for some upcoming specific time.
e. Use model to show why eclipses are so rare
e. Explain why the moon rise is 1 hour time difference each night.
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