A Walk Across the Solar System Subject Area: Earth Science and Mathematics Grade Level: Grades 4 and 8 Lesson Objective: Duration: Students will help create a model of the solar system in which the scale for both the size of the planets and the distances in the solar system is 1 inch = 100,000 miles. Hopefully, the students will be amazed by the amount of space vs. mass in the solar system. This activity will require students to use basic math skills, the formula for circumference, decimal numbers, averages, and measurement. 60 minutes Standards Correlation: Grade 4 Astronomy Standard 4-3: The student will demonstrate an understanding of the properties, movements, and locations of objects in the solar system. (Earth Science) 3.1 Recall that Earth is one of many planets in the solar system that orbit the Sun. 3.3 Explain how the Sun affects Earth. 3.8 Recognize the purpose of telescopes. Grade 4 Mathematics Number and Operations Standard 4-2: The student will demonstrate through the mathematical processes an understanding of decimal notation as an extension of the place-value system; the relationship between fractions and decimals; the multiplication of whole numbers; and accurate, efficient, and generalizable methods of dividing whole numbers, adding decimals, and subtracting decimals. 2.10 Identify common the fraction/decimal equivalents Algebra Standard 4-3: The student will demonstrate through the mathematical processes an understanding of numeric and nonnumeric patterns, the representation of simple mathematical relationships, and the application of procedures to find the value of an unknown. 3.3 Use a rule to complete a sequence or a table. Updated August 2007 1 Darlene Smalley
Measurement Standard 4-5: The student will demonstrate through the mathematical processes an understanding of elapsed time; conversions within the U.S. Customary System; and accurate, efficient, and generalizable methods of determining area. 5.3 Use equivalencies to convert units of measure within the U.S. Customary System: converting length in inches, feet, yards, and miles; converting weight in ounces, pounds, and tons; converting liquid volume in cups, pints, quarts, and gallons; and converting time in years, months, weeks, days, hours, minutes, and seconds. Data Analysis and Probability Standard 4-6: The student will demonstrate through the mathematical processes an understanding of the impact of data-collection methods, the appropriate graph for categorical or numerical data, and the analysis of possible outcomes for a simple event. 6.3 Organize data in tables, line graphs, and bar graphs whose scale increments are greater than or equal to 1. Grade 8 Astronomy: Earth and Space Systems Standard 8-4: The student will demonstrate an understanding of the characteristics, structure, and predictable motions of celestial bodies. (Earth Science) 4.1 Summarize the characteristics and movements of objects in the solar system (including planets, moons, asteroids, comets, and meteors). 4.6 Explain how gravitational forces are influenced by mass and distance. 4.7 Explain the effects of gravity on tides and planetary orbits. 4.8 Explain the difference between mass and weight by using the concept of gravitational force. Grade 8 Mathematics Number and Operations Standard 8-2: The student will demonstrate through the mathematical processes an understanding of operations with integers, the effects of multiplying and dividing with rational numbers, the comparative magnitude of rational and irrational numbers, the approximation of cube and square roots, and the application of proportional reasoning. 2.1 Apply an algorithm to add, subtract, multiply, and divide integers. Measurement Standard 8-5: The student will demonstrate through the mathematical processes an understanding of the proportionality of similar figures; the necessary levels of accuracy and precision in measurement; the Updated August 2007 2 Darlene Smalley
use of formulas to determine circumference, perimeter, area, and volume; and the use of conversions within and between the U.S. Customary System and the metric system.. 5.7 Use multistep unit analysis to convert between and within U.S. Customary System and the metric system. Required Materials: Objects to represent the 9 planets and the sun Flags to mark planet locations during the walk Color images on cardstock of the planets and the sun Planet chart with diameter and distance data (cardstock and transparency) String and ruler for measuring circumference of sun ball Scientific calculators for each student or pair of students Measuring wheel to be used when determining pace length Paper and pencils for recording data Student handout: Planet Chart Procedure: 1. Engage students and evaluate their knowledge of the solar system Introduce the topic of the solar system by asking the students what it is. Hand someone the picture of the sun and hand out pictures of the planets to other students as they tell me the correct order of the planets from the sun out to Pluto. Ask the students with the pictures to now arrange themselves in order by size from the largest object to the smallest. The correct order and diameters are: Sun 865,000 miles, Jupiter 89,000 miles, Saturn 75,000 miles, Uranus 32,000 miles, Neptune 31,000 miles, Earth 8,000 miles, Venus 7,500 miles, Mars 4,000 miles, Mercury 3,000 miles, and Pluto 1,500 miles. Show students a list of planet diameters (with the planets in order from the sun out) if they need help figuring out the size order. 2. Introduce the goal of an accurate model and show an inaccurate one Once they have arranged themselves correctly, tell students we are going to spend the rest of our time creating a model of the solar system. Bring out the orrery as an example of a model of the solar system that is useful but not very accurate. It shows the planets in the correct order, and it correctly shows the orbital speeds of the planets when it is turned on, but it does not accurately represent the sizes of the planets or the distances between them. Tell them I want them to help me create a more accurate model which uses the same scale for object diameter and for distance. Hand out student copies of the planet chart. 3. Introduce the objects to be used in the model; develop critical thinking Hand a student the sun ball and ask, If we use this yellow ball to represent the sun in our model, how big do you think Jupiter, the next biggest object, should be? Listen to their answers, then bring out the correct model. Swap the Jupiter model for the Jupiter photo card. Now ask, How big do you think Pluto will be in this model? Listen for answers, then swap the Pluto model for the Pluto photo card. Next, bring out the rest of the model planets and swap them for the photo cards. Have the students examine the models, and ask them how they could determine the scale for the model we are using. We need to know this so we can figure out how far apart to put the planets. If they have a hard time thinking Updated August 2007 3 Darlene Smalley
of an answer, refer them to the actual diameter data (on the board or an overhead) and ask how they could determine the diameter of our model sun using string, a yardstick, and a calculator. Hold up these items and invite the students to think about the measurement and formula required. 4. Students measure and do calculations to determine model scale Students should measure the circumference of the sun ball and use a calculator to figure out the diameter. Ask them to figure out the scale of our model by comparing the actual diameter of the sun to that of the ball. (Divide 860,000 miles by 8.6 inches to get 100,000 miles = 1 inch.) Using this scale, ask them to calculate the model diameter in inches for each of the planets. Tell them not to use calculators and to give the answer as a decimal number rounded to the nearest hundredth of an inch. Do Jupiter together, then tell students to do the rest on their own. Or, continue to work together as a class. Write the numbers they come up with on the board or overhead as students fill in these numbers on their own planet charts. 5. Develop reasoning skills through prediction and determination of pace length Ask them how much space they think we will need to accurately model the distances to the planets using the same scale of 1 inch = 100,000 miles. Accept their answers and discuss. When they realize that we ll have to go outside, tell them we will need to pace off the distances between planets, so we will need to figure out our pace lengths. Ask for volunteers who don t have a planet, to come up and measure their pace length. Have them walk between two pieces of tape on the floor 3 times, carefully counting the number of paces(steps) they take each time. They should average their 3 trials and share the result. At that point, have students measure the distance walked using a long measuring tape, and have students calculate the pace lengths of the walkers. 6. Make learning fun! Go for the planet walk. It s now time to go outside and walk! Have students bring the model sun and planets plus the flags. Walk westward in front of the RPSEC into the grass beyond the last driveway. Set down the sun ball and begin the walk across the solar system in an easterly direction along the curb in front of the building. Have the student with a pace closest to a yard walk at the front with me to count the number of paces required to reach the next planet. The instructor should have a card that lists the number of paces between successive planets and should reveal only one number at a time, the paces to the next planet. Hopefully, this will build some excitement and suspense. As each planet location is reached, lay the card holding that model on the ground and mark the spot with a flag so that you can find the model again on the return trip. Stop and look back at the sun from each planet, noticing its decreasing size. Talk about how the increasing distance from the sun effects the planets. When I do this, I turn right shortly before reaching University Parkway. Then, we continue to walk parallel to that road but in the grass until we come to the last entrance to the college. At this point, I turn left and cross the parkway, then we end up crossing the entrance road to the hospital so that we can finish the walk on the walking trail by the hospital. If you are somewhere else, just determine a relatively straight course 1019 yards long. This is over half a mile! Most people will be awed by the incredible amount of space in the solar system compared with the small amount of mass. After the students rest a few minutes by Pluto, head back to the classroom, picking up the planet models as you go. The flags make this easy; otherwise, you ll have to count paces carefully on the walk back, too, and probably will still have to search for the cards. 7. Students chart data and calculate distances from the sun When students return to the building, give them time to get a drink and use the bathroom. Then use Updated August 2007 4 Darlene Smalley
whatever time remains to fill in data on the planet chart. Give them the number of paces from the previous planet (for Mercury, the # from the sun), and have students complete the paces from the sun column and the miles from the sun column. Make sure all students know that one pace (one yard) in our model = 3,600,000 miles. They can use calculators, but tell them you want the answers listed using scientific notation. Briefly review how to write large numbers using scientific notation. This lesson is an adaptation and expansion of The Thousand-Yard Model by Guy Ottewell. It is in the Project ASTRO Resource Notebook published by the Astronomical Society of the Pacific. A copy of that lesson is included with this lesson plan for the benefit of the instructor. Updated August 2007 5 Darlene Smalley