Seasons (Observable Patterns)

Transcription

1 Seasons (Observable Patterns) E Q U I T A B L E S C I E N C E C U R R I C U L U M Lesson 3 i N T E G R A T I N G A R T S i n P U B L I C E D U C A T I O N NGSS Science Standard: 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. Disciplinary Core Idea: 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. Student Learning Objectives: Using a mini globe model of the earth and a template worksheet, students will be able to simulate the earth revolving around the sun during different times of the year. Students will learn that the tilt of the earth on its axis and the amount and duration of sunlight the earth receives are the cause for the seasons. They will learn that the summer is generally warmer because the earth is positioned toward the sun and the days are longer in summer. They will learn that the earth is actually farther from the sun during summer than it is during winter in the northern hemisphere due to the slightly elliptical orbit of the earth around the sun. MISCONCEPTION: The summer season is warmer due to the earth being closer to the sun. Mosart question 14. What happens as summer changes to fall? Possible Preconceptions/Misconceptions: The earth is larger than the sun. We experience seasons because of the earth s changing distance from the sun (closer in the summer, farther in the winter). The sun revolves around the earth. Seasonal changes do not occur in a predictable pattern. The amount of daylight increases each day of summer. STEM Earth Systems Lesson 3 Page 1

2 BRIEF LESSON DESCRIPTION: Students will use a model of the earth to show how it revolves around the sun to help the students visualize the reason for the seasons. Many places on the earth experience four seasons: summer, autumn, winter, and spring. The seasons occur because of the tilt of the earth on its axis as it revolves around the sun. Because of the earth s tilt, the surface of our planet is unevenly heated. Whenever one of the earth s hemispheres is more positioned toward the sun it receives a greater amount of less spread out solar energy (light). In the summer season in the Northern Hemisphere the earth is actually farther from the sun than it is during winter. Many students have the misconception that summer occurs because the earth is closer to the sun. Vocabulary Tier 2: revolution- The movement of a planet around the sun. Note -The term orbit is used interchangeably with the term revolve when orbit is used as a verb. axis- The line about which a rotating body, such as the earth, turns system- A group of related parts that move or work together patterns- The regular and repeated way in which something happens or is done. year- One complete revolution of the earth around the sun or 365 days. Note- A complete revolution around the sun actually takes days so every four years we have a leap year with an extra day on February 29th to account for this. Tier 3: orbit- (noun) A path of an object as it circles around another object in outer space. equator- An imaginary line running around the earth halfway between the north and south pole. northern hemisphere- The half of the earth above the equator. southern hemisphere- The half of the earth south of the equator. counterclockwise- In a direction opposite of the hands of a clock. Background Information: Seasons are caused because the earth is tilted on its axis. The earth s axial tilt is at an angle of 23.5 degrees relative to the plane of the ecliptic, its plane of orbit around the sun. During summer the Northern Hemisphere is positioned towards the sun, while the Southern Hemisphere is positioned away. During the next several months as the earth revolves around the sun, the situation is reversed. Whichever hemisphere is positioned towards the sun as it revolves around the sun experiences more energy or more direct light over a longer day and warms up. The hemisphere positioned away from the sun has winter and receives more spread light or less energy, has a shorter day, and cools down. When summer begins on June 21st the Northern Hemisphere, the earth is positioned towards the STEM Earth Systems Lesson 3 Page 2

3 sun. This is known as the summer solstice, and when it s positioned away from the sun in late December, that s the winter solstice. When both hemispheres receive nearly equal amounts of energy, it s called the equinox. We have a spring equinox, and then an autumn equinox, when our days and nights are nearly equal in length. Equinox literally means equal night. Whichever hemisphere is positioned towards the sun experiences more energy or direct light, and warms up, while the hemisphere positioned away receives spread light and less energy and cools down. Consider the amount of solar radiation falling on part of the earth. When the sun is directly overhead, each square meter of Earth receives about 1,000 watts of energy. But when the sun is at a severe angle, like at the poles, the same 1,000 watts of energy is spread out over a much larger surface area. This also explains why the days are longer in the summer, and then shorter in the winter. Since the days are longer during summer the hemisphere having summer receives more solar energy over a longer daytime so it becomes warmer. Materials Per student: Crayons Per group: Copy of Seasons template included in lesson. Note many copy machines will allow for a larger size copy to be made from the original Seasons template. Use a larger sized template if possible. Mini globe pencil sharpeners. They are inexpensive and available online through many websites. One source is Per class: Classroom Globe STEM Earth Systems Lesson 3 Page 3

4 Engage Show pictures of the earth in different seasons. Ask, What are the names of the four seasons? What is the order of the four seasons? Explore/Lesson Procedures: Inquiry questions. 1. Why does the earth have seasons during the year? How does the earth tilting on its axis result in seasonal changes? Part A: 1. Ask the inquiry questions. Take responses to the questions from several students. Explain that the activities in this lesson will help them learn why we have seasons. 2. Using the Seasons Template students should color the sun yellow and label the name of the seasons on the worksheet. In the Northern Hemisphere summer begins on June 21st, fall begins on September 23rd, winter on December 21st, and spring on March 20th. If time permits at the end of the lesson, the students can draw illustrations in the picture frames of an activity they might do during each season. 3. Have the students place the mini globe at the bottom of the page with the axis pointing toward the top of the page as pictured. Optional- a small yellow ball or small yellow balloon could be used to represent the sun. 4. Have the students observe the globe. Show a large globe to assist with locating the axis and equator. Ask, where is the equator? Ask, how does it divide the earth? Answer, into two equal STEM Earth Systems Lesson 3 Page 4

5 hemispheres north and south. Where is the axis of the earth? Answer, the posts at the top and bottom of the globe. Picture of the earth mini globe as it must be situated on the template. Note that the arm of the globe points straight up toward the top of the page and the earth s axis also points to the top of the page. The arm of the globe must stay in the same position, pointing up to the top of the page, as the earth revolves around the sun. 5. Ask, what is a year? Answer one complete revolution around the sun or 365 days. The actual complete revolution takes days and to balance the calendar the.25 day is not counted until a leap year which occurs every four years. 6. Keeping the mini globe with the axis pointing to the top of the page and revolving counter clockwise have students start at summer and complete one trip or revolution around the sun until they are back to summer at June 21st. Ask what does this represent? Answer, one year or one complete revolution of the earth around the sun. Monitor students while they do this to be sure they keep the axis oriented correctly. 7. Next have the students make two complete trips or revolutions around the sun to show two complete years. Students may rotate the earth (counterclockwise) as it revolves around the sun but they need to keep the axis pointing correctly to the top of the page. The tilt of the earth does not change during this activity. 8. Put the earth at the start of summer again and ask students, Which hemisphere is receiving direct light from the sun on June 21st? Answer, the Northern Hemisphere. Ask, what happens to the weather when the sun s energy is more directed on one hemisphere? (The season becomes summer and the days get longer which results in warmer weather.) 9. Ask students, what happens to the length of daylight during summer compared to the length STEM Earth Systems Lesson 3 Page 5

6 of daylight in winter? Answer, the days are longer in summer than in winter due to the position of the earth as it revolves around the sun. 10. Ask, how does the longer day affect the weather during summer? Answer, it gets warmer because the sun is shining on the earth during summer for a longer period of time. 11. Keeping the axis pointing to the top of the page, students will revolve, counterclockwise, to the September 23rd line and ask students: Which hemisphere is receiving the most solar energy from the sun? (Answer: both are about equal and the length of day is about the same at a given latitude.) 12. Ask: What happens to the weather when the sun s energy is directed almost equally on both hemispheres? (Answer: The Northern Hemisphere is experiencing Autumn/Fall and that results in cooler weather than in summer.) 13. Now revolve (orbit) to the line marked December 21st at the top of the page. Ask students: Which hemisphere is receiving the more direct light from the sun? Answer, the Southern Hemisphere. What happens to the weather when the sun s energy (light) is more spread out on the northern hemisphere? (The season changes to winter and results in colder weather with shorter days.) 14. Emphasize scientists have measured that the earth is actually closer to the sun in the winter in the northern hemisphere as the earth s orbit is not a perfect circle, and that the position of the earth on its axis, relative to the sun, is the cause of the seasons. Ask, is it correct to say that the earth being closer to the sun in the northern hemisphere is the cause of summer? Answer, no! 15. Revolve counterclockwise to the spring or March line. Ask the students to describe how much sunlight each hemisphere is receiving. Students should observe that the northern and southern hemispheres again are getting about the same amount of solar energy and evenly spread out. 16. Ask students: Which hemisphere is receiving the most solar energy from the sun? Answer, they are the same as both are receiving light evenly spread light. Ask, What happens to the weather when the sun s energy (light) is about equally spread out on both hemispheres? Answer, spring in the Northern Hemisphere and slightly warmer weather, and fall in the Southern Hemisphere. 17. The teacher chooses a season and has the students orient the earth model, in its proper position, on the template. (Teacher monitors that the axis is always pointing to the top of the page). Be sure students each get a turn or two doing this. 18. Do this several times and with a variety of seasons. In table teams students should move the model to a particular season and explain why the season they are modeling is occurring. Take responses from several groups. 19. If time permits, have students draw illustrations depicting an activity that they might do during that season in the in the areas provided for each season. Part B 1. Watch the Bill Nye video Earth s Tilt (5:38) Video: Earth s Tilt 1: The Reason for the Seasons 2. Ask students, why was it a different season in Australia than in the United States? Answer, the Southern Hemisphere has the opposite season that the Northern Hemisphere has. STEM Earth Systems Lesson 3 Page 6

7 In Australia June 21st is the first day of winter and in the northern hemisphere it is the first day of summer because of the tilt of the earth on its axis as it revolves around the sun. Evaluate Have students write in their science notebooks and ask students to write their understanding of why the seasons occur. Encourage students to use academic vocabulary in their explanations. ELL Modification: Encourage table talk in teams. Hearing language and listening to how academic vocabulary is used, are valuable strategies for ELL students. Encourage students to work with a partner as they write their explanations. ELL Modifications: Write vocabulary words on the board or butcher paper to create a word bank. Use student partners at each table group to practice vocabulary during group work. Have the students copy and complete the sentence frames in their journals to aid students understanding of the vocabulary. 1. The earth is 23.5 degrees on its. (tilted, axis) 2. In the summer, in the northern hemisphere, the earth is positioned so that the light from the sun is. (more direct, or less spread out) 3. In in the northern hemisphere the earth is positioned so that the sunlight is more. (winter, spread out) 4. The seasons change as the revolves around the. (earth, sun) 5. During winter the daylight hours are than in summer so it is. (shorter, colder) 6. Summer is not caused by the earth being to the sun. (closer) STEM Earth Systems Lesson 3 Page 7

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