Moon Watch. Observing the Lunar Phases with a Model. marker, Sharpie

Transcription

1 Middle Grades Science Moon Watch Observing the Lunar Phases with a Model MATERIALS AND RESOURCES EACH GROUP adhesive, reusable copy of Lunar Layout sheet (laminated) ping pong ball protractor, with hole TEACHER marker, Sharpie ABOUT THIS LESSON This activity involves an inexpensive, handson, minds-on, and exciting way for students to experience the phases of the Moon. It provides a deep, rich context for scientific understanding of the natural world. Students will discover that the phases of the Moon are not random but occur in a regular, predictable fashion. OBJECTIVES Students will: Determine the cause of the lunar phases as well as name the phases using a representative model LEVEL Middle Grades: Earth Science i

2 COMMON CORE STATE STANDARDS 6.EE.7 Solve real-world and mathematical problems by writing and solving equations of the form x + p = q and px = q for cases in which p, q and x are all nonnegative rational numbers. 6.RP.3B Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations. Solve unit rate problems including those involving unit pricing and constant speed. For example, If it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were lawns being mowed? 6.RP.3D Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations. Use ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities. 7.EE.3 Solve multi-step real-life and mathematical problems posed with positive and negative rational numbers in any form (whole numbers, fractions, and decimals), using tools strategically. Apply properties of operations as strategies to calculate with numbers in any form; convert between forms as appropriate; and assess the reasonableness of answers using mental computation and estimation strategies. For example: If a woman making $25 an hour gets a 10% raise, she will make an additional 1/10 of her salary an hour, or $2.50, for a new salary of $ If you want to place a towel bar 9 3/4 inches long in the center of a door that is 27 1/2 inches wide, you will need to place the bar about 9 inches from each edge; this estimate can be used as a check on the exact computation. RH Distinguish among fact, opinion, and reasoned judgment in a text. (LITERACY) RST Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks. (LITERACY) RST By the end of grade 8, read and comprehend science/ technical texts in the grades 6-8 text complexity band independently and proficiently. (LITERACY) W.1 Write arguments to support claims in an analysis of substantive topics or texts, using valid reasoning and relevant and sufficient evidence. v. 3.0, 3.0 ii

3 ASSESSMENTS The following types of assessments are embedded in this activity: Assessment of prior knowledge Pre-lab discussion Formative assessment questions Summative assessment activity The following additional assessments are located on our website: Middle Grades Assessment: Space Science Earth-Moon-Solar System Short Lesson Assessment: Moon Watch NEXT GENERATION SCIENCE STANDARDS DEVELOPING AND USING MODELS PATTERNS ACKNOWLEDGEMENTS Sharpie is a registered trademark of Sanford L.P., A Newell Rubbermaid Company. REFERENCES Espenak, Fred. Mr. Eclipse. Background information describing how solar and lunar eclipses occur. HeyWhatsThat: Eclipses. Simulations of solar and lunar eclipses, past and future. Kavanagh, Claudine, Lori Agan, and Cary Sneider. Learning about Phases of the Moon and Eclipses: A Guide for Teachers and Curriculum Developers. Astronomy Education Review 4.1 (2005): Review of research studies that focus on the misconceptions students have about the phases of the Moon and different teaching methods. ESS1: THE UNIVERSE Lunar Cycle 1: Calendar. Science NetLinks. American Association for the Advancement of Science. Resource for generating calendars that students can use to create a Moon watch journal. Lunar Cycle 2: The Challenge. Science NetLinks. American Association for the Advancement of Science. Online activity that challenges participants to predict the phase of the Moon based on past and future Moon phases. Lunar Phase Simulator. Astronomy Education at University of Nebraska Lincoln. Online simulation that demonstrates how the Sun-Earth-Moon angle causes the phases of the Moon. iii

4 TEACHING SUGGESTIONS Inuit legend tells of the moon god Annigan chasing his sister Malina, the sun goddess, through the sky. When the full moon wanes and become the new moon, Annigan is weak from the chase and becomes thinner. When he eats and is reinvigorated, the moon waxes and becomes full. Although we no longer ascribe the phases of the moon to activities of deities, our lunar fascination has not waned. Indeed, one of our greatest scientific and engineering achievements is the lunar landing, and efforts to visit our closest celestial neighbor continue to this day. Still, misconceptions about the Moon persist. Students and adults alike believe the phases of the Moon are the result of the Moon passing through the Earth s shadow. Although the passing of a celestial body through the shadow of another celestial body causes an eclipse, it is the angle between the Sun, Earth, and Moon that causes the Moon s changing appearance (Figure A). Only when the Sun, Earth, and Moon are in the same plane can a lunar eclipse occur. Light from the Sun radiates in all directions, therefore all objects in the solar system are illuminated by the Sun, including the Moon. However, because only half of any object can face the Sun, only the sun-facing half is illuminated. A new moon occurs when the unilluminated half of the Moon faces Earth and the Moon disappears from the sky (Figure B).. Figure A. The orbit of the Moon is tilted 5 degrees with respect to the plane of the Earth s orbit with the Sun. Understanding the phases of the Moon can be quite difficult, and there are a number of models to help your students explore how the phases of the Moon occur. One of the most popular and delicious uses chocolate sandwich cookies. Students separate the cookie halves and scrape away the cream to recreate the moon phases. This activity is great for getting students to recognize the Moon s phases but does nothing to help students learn how they occur. Another model uses a light source and spherical objects to demonstrate how the changing angle between the Sun, Earth, and Moon cause the phases. This model illustrates the process of the Moon s phases, but it can be unwieldy owing to the amount of space needed to conduct the activity. It is also difficult to ensure that all your students are able to see the Moon s phases uniformly. iv

5 TEACHING SUGGESTIONS (CONTINUED) The ping pong ball model used in Moon Watch addresses the disadvantages of the previous models: the students are able to recognize the Moon s phases and see how they occur without needing all the space of the light source model. Students place the moon on the lunar layout sheet, making sure that the illuminated side of the moon always faces the sun, and then they view the moon from an earthly perspective. As the moon orbits the earth, new moon to full moon and back again, the phases are seen as a continuum. The changing angle between the sun, earth and moon give rise to the moon s phases: first waxing crescent, quarter moon, waxing gibbous, full moon, waning gibbous, waning crescent, and the cycle begins again. To prepare students for this activity and ascertain prior knowledge about the Moon, ask your students to go outside and observe the Moon six to eight weeks before the start of the activity. In lieu of keeping a journal, students can take pictures of the Moon using a digital camera or the camera available on various smartphones. Other options include providing your students with a calendar template with room to sketch the appearance of the Moon and provide any ancillary comments. You may want to suggest that your students make observations around sunset to avoid having them out too late at night. However the students make their observations, encourage them to be as consistent as possible when taking their pictures, paying close attention to the time and location. If your students take digital images of the Moon, ask them to their photos to you for use in a summative assessment piece. Figure B. When the Moon appears full, the Moon is opposite the Sun and the full illuminated portion of the Moon is visible v

6 TEACHING SUGGESTIONS (CONTINUED) During your pre-lab discussion, direct your students to take a few minutes and view their pictures in chronological order. The following questions could be used during your pre-lab discussion: What words could you use to describe the way the Moon looks? Where does the Moon get its light? What patterns do you see in the way the Moon looks at night? Is there a correlation between the time of the month and the phase of the Moon? What do you think causes the changing appearance of the Moon? The mechanics of Moon Watch are simple. Students will move a ping pong moon through its orbit around the earth and sketch the moon s appearance from their vantage point on earth. Because the Sun illuminates half of the Moon at all times, half of the ping pong moon will be painted black to demonstrate the unilluminated portion of the Moon. The remaining half will remain white to represent the illuminated side. Our earthly perspective prevents us from seeing the full illuminated portion, and gives rise to the phases of the Moon. Many lunar phases activities use a light source and a sphere to model the Moon s changing appearance, but it is difficult to determine if all students have seen the phase from the correct angle, if they have actually seen what is intended, and if they understand that half of the Moon is always illuminated. With this model, half of the sphere will always be white, and thus illuminated. Formative assessment questions you can use during the activity and before the Conclusion Questions may include: Does every waxing crescent look the same? Every waning gibbous? Do the terms crescent and gibbous refer to a specific phase of the Moon? What is the difference between a new moon and a full moon? Can you think of factors not accounted for in this model? At the end of the activity, have students demonstrate their understanding of the phases of the Moon by using their photos to create cards showing the phases. Place the cards in a container, and have students pick a card and reproduce the phase of the Moon pictured on their card by placing the ping pong ball in the correct location. You may also use the lunar phases simulator created by the University of Nebraska Lincoln Astronomy Education Group ( Figure C). Ping pong balls can be purchased at sporting goods suppliers or other discount stores. You may substitute another small sphere to take the place of the ping pong ball, such as a polystyrene ball or wooden drawer pulls. To color the ping pong ball half black and half white, use permanent marker or black spray paint. When looking at the ping pong ball, find the seam along the mid-line and lay painter s tape or masking tape along this seam. This will ensure that only half of the ball will be painted. vi

7 TEACHING SUGGESTIONS (CONTINUED) Figure C. By turning off the moon phase display, you can project the simulation and place the moon in various positions and have the students predict the phase of the moon. Students must have the white half of the Moon facing the side of the paper where the Sun is positioned. One way to help with this setup is to tell students to keep the mid-line of the ping pong ball aligned with the vertical line at each location. Also, students must observe the Moon phase as if standing on Earth in the middle of the Lunar Layout sheet. They must observe the ping pong ball with their head level with the paper, and look along the line that connects the Moon and Earth. The reusable adhesive is used to keep the ping pong ball in place. This adhesive could be the material that holds posters on walls, modeling clay or, if your Lunar Layout sheets are laminated, the students could use tape. Any material that will temporarily allow the Moon to sit in the correct orientation on the Lunar Layout sheet will work. Some students may not be familiar with protractors and may require help. Test their prior knowledge by asking students how to use the protractor or measure given angles. The important thing to remind them is that measurements should range from 0 to almost 360. In other words, they should not start over at 0 once they measure past 180. A few notes of explanation: The angle measures for the different phases are not equal increments. Using this setup, a student cannot simply find the pattern and add the increment to avoid using the protractor. There are multiple waxing and waning phases to emphasize that there exist a continuum of waxing or waning phases between the new moon, full moon, and quarter moons. vii

8 ANSWER KEY DATA AND OBSERVATIONS Table 1. Phases of the Moon Position Sketch of Moon Angle Measure Phase Name 1 0 New moon 2 23 Waxing crescent 3 67 Waxing crescent 4 90 First quarter Waxing gibbous Waxing gibbous Full moon Waning gibbous Waning gibbous Third quarter Waning crescent Waning crescent vii

9 ANSWER KEY (CONTINUED) CONCLUSION QUESTIONS 1. Each lunar cycle includes one new moon. Every 29.5 days, we observe a new moon from Earth. 2. A waning crescent is visible for 7.4 days. The phases between a third quarter moon and a new moon are all waning crescents. A third quarter moon is three quarters of the way through the 29.5-day cycle, and a full moon would be halfway through the cycle. From Day 22.1 (29.5 ¾) to Day 29.5 would be 7.4 days of waning crescent. 180 x days 22 days x(14 days) (22 days)(180 ) 3960 days x days The actual mathematical value is , or with the correct number of significant digits. 4. To show the lunar cycle in the Sou thern Hemisphere, you would move the ping pong ball around the Lunar Layout in reverse order (1, 12, 11, 10 2). 5. Answers will vary but may include lack of rotation of the Moon on its axis, the size of the model, and the relative distance between celestial bodies. 6. The lunar cycle is 29.5 days whereas most months are 30 or 31 days. If a full moon occurs within the first three days of a month, we would have a second full moon before the month is over. viii

10 Moon Watch Middle Grades Science Observing the Lunar Phases with a Model MATERIALS adhesive, reusable copy of Lunar Layout sheet (laminated) ping pong ball protractor, with hole The Moon goes through a continuous repetition of its phases as it orbits Earth. The average duration of one cycle is 29.5 days. A lunation, or complete cycle of the moon phases, begins with a new moon. A new moon is the phase when the Moon is not visible; the illuminated side of the Moon is facing away from Earth. Except during a lunar eclipse, half of the Moon is always illuminated. The different phases are caused by the illuminated surface of the Moon not always being visible from Earth. The halfway point of a lunation is a full moon, when the entire illuminated side of the Moon is visible from Earth. The other phases are all in-between steps of the cycle from new moon to full moon to new moon. When we can see more of the illuminated side than the previous night, the Moon is considered to be in its waxing phases. When the illuminated portion is smaller than the previous night, the Moon is considered to be in its waning phases. For example, if you can see half of the Moon one night and the next night you can see more than half, the Moon is waxing. Another pair of descriptive terms used in naming lunar phases are gibbous and crescent. A gibbous moon occurs when the Moon is more than half visible, and a crescent moon occurs when the Moon is less than half visible (Figure 1). Figure 1. Gibbous and crescent moons Gibbous Crescent 1

11 In the northern hemisphere, a new moon becomes illuminated from the right to the left and a full moon becomes dark from right to left. If you see a moon that looks similar to the gibbous diagram shown in Figure 1, you know it must be a waning gibbous as the illumination on the Moon is moving toward a new moon, not a full moon. If you see a moon similar to the crescent in Figure 1, you know it is a waxing crescent as the illumination is starting from the right and is moving toward a full moon. Figure 2. First and third quarters First Quarter Third Quarter Halfway between a new moon and full moon there is a phase where the right half of the Moon appears illuminated. This phase is known as the first quarter (Figure 2). Halfway between the full moon and new moon, the left half of the Moon appears illuminated. This phase is known as the third quarter (sometimes known as the last quarter). There are several days of waxing crescents but only one first quarter. The same applies for all crescent and gibbous moons. PURPOSE You will use a model to determine the cause of the lunar phases, as well as name the phases. 2

12 PROCEDURE 1. Place the small amount of adhesive on the ping pong ball in one place where the white and black sections meet (see Figure 3). Figure 3. Colored ping pong ball ping pong ball reusable adhesive 2. Place the ping pong ball (adhesive side down) on the circle at Position 1 of the Lunar Layout sheet where the straight line and arc of the circle intersect. The white part of the ping pong ball should be facing the direction of the Sun at all times. Align the mid-line of the ping pong ball with the vertical line at Position 1. This signifies that half of the Moon is always illuminated even though we do not always see the illuminated side. 3. Observe the ping pong ball from the level of the paper, looking along the straight line from the location of Earth to Position 1 as if you were standing on Earth. Fill in the circle on your data sheet so that it reflects the image you observe. The angle measurement for Position 1 will be 0. For the remainder of the positions, you will use your protractor to measure the angle based on Position 1. Position 8 through Position 12 will have angle measures greater than 180. Based on the introductory descriptions of the different phases and the image you observed, name the lunar phase modeled at Position Remove the ping pong ball from Position 1 and, using the adhesive, mount the ping pong ball at Position 2. Remember to orient the white side of the ping pong ball so it faces the side where the Sun is positioned (Figure 4). Figure 4. Position of ping pong ball 5. Complete Step 3 and Step 4 with the ping pong ball positioned at all 12 locations. Be sure to always observe the ping pong ball while looking along the line from the location of Earth to the position of the ball. 3

13 DATA AND OBSERVATIONS Table 1. Phases of the Moon Position Sketch of Moon Angle Measure Phase Name

14 CONCLUSION QUESTIONS 1. A friend says there are two new moons during any given lunar cycle. Explain why you agree or disagree. 2. Calculate the number of days during any given lunar cycle when a waning crescent is visible. Show your work. 3. If a full moon is approximately Day 14 of the lunar cycle, what would the angle measure be for Day 22? Use your angle measure for a full moon to set up a proportion, and show your work and all units. 4. While the Northern Hemisphere is experiencing a waxing crescent from the right, the Southern Hemisphere is experiencing a waxing crescent from the left. Both hemispheres experience a new moon or a full moon on the same day, but the rest of the phases are seen from opposite directions. How could you use the model (the ping pong ball and Lunar Layout sheet) to show the lunar cycle as experienced in the Southern Hemisphere? 5

15 CONCLUSION QUESTIONS (CONTINUED) 5. What are three limitations of the model used in this activity? 6. Approximately every 2.7 years, we experience a blue moon, or a second full moon in one month. How is this possible? 6

16 L E S S O N C O N S U M A B L E 7