H.S. Solar Energy: The Sun and its Core

Transcription

1 D R I G r e e n P o w e r P r o g r a m G r e e n B o x H.S. Solar Energy: The Sun and its Core Created by: Learning Cycle 5E Lesson Based upon and modified from Roger Bybee* (1990) *Bybee, R & Landes, N. (1990). Science for life and living: An elementary school science program from Biological Sciences Curriculum Study (BSCS). American Biology Teacher. 52 (2)

2 The Sun and its Core Next Generation Science Standards (NGSS) Physical Science: HS-PS1-8. Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay. HS-PS1-4. Develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy. HS-PS3-3. Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy. HS-PS3-2. Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative positions of particles (objects). HS-PS1-3. Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles. Earth and Space Science: HS-ESS1-3. Communicate scientific ideas about the way stars, over their life cycle, produce elements. HS-ESS1-1. Develop a model based on evidence to illustrate the life span of the sun and the role of nuclear fusion in the sun s core to release energy in the form of radiation. Background Knowledge Teacher: The sun is just one of more than 200 billion stars in the Milky Way galaxy, and the Milky Way is just one of hundreds of billions of galaxies in the universe. The sun is by far the biggest thing in the solar system. From its distance of almost 150 million kilometers, its diameter is determined to be 1,392,000 kilometers. This is equal to 109 Earth diameters and almost 10 times the size of the largest planet, Jupiter. All of the planets orbit the sun because of its enormous gravity. It has about 333,000 times the Earth's mass. It has so much mass that it is able to produce its own light. This feature is what distinguishes stars from planets. Nearly all observable matter in the universe is hydrogen or helium, which formed in the first minutes after the Big Bang. Elements other than these remnants of the Big Bang continue to form within the cores of stars. What is the sun made of? Solar Energy Green Box: Lesson 1 The Sun and its Core 2

3 Spectroscopy shows that hydrogen makes up about 94% of the solar material, helium makes up about 6% of the sun, and all the other elements make up just 0.13% (with oxygen, carbon, and nitrogen the three most abundant ``metals''---they make up 0.11%). The sun also has traces of neon, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, potassium, and iron. Stars shine because of nuclear fusion reactions in their core. Nuclear fusion is a proton-proton chain reaction where 4 hydrogen nuclei (protons) fuse in an environment of very high pressure to become a helium atom. During this process photons (gamma-rays) are released. Photons (which convert to light and heat energy amongst other forms of energy) radiate from the sun s core to make life on Earth possible. The more luminous a star is, the more reactions are taking place in their cores. Massive stars (like the sun) live shorter lives than the common small stars because even though they have a larger amount of hydrogen for nuclear reactions, their rate of consuming their fuel is very much greater. The massive stars can be compared to large, gas-guzzling SUVs with big gas tanks and the small stars are like the small economy cars that don t use a lot of gas. The sun is a medium-sized star about halfway through its predicted life span of about 10 billion years. References: Nick Strobel s Astronomy Notes, A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas Student: A. Prior Standards: a. MS-PS1.A: Structure and Properties of Matter b. MS-PS4.B Electromagnetic Radiation c. MS-ESS1.A The Universe and its Stars d. MS-ESS2.A and MS-ESS2.D Earth's Systems B. Life Experience: Students have extensive life experience with this topic through their lifetime of interaction with the sun. They can relate to heat and light on a very personal level. At this stage they are also familiar with the concept of photosynthesis and the need for the sun s light for all plants to grow. Solar Energy Green Box: Lesson 1 The Sun and its Core 3

4 Time minutes Materials List Student Guides for each student Sun and its Core PowerPoint Popcorn maker: 1 or 2 Popcorn: Enough for entire class Digital Scale: 1 or 2 Small-medium bowls: 1 for each group of 3-4 students Two larger bowls or buckets (to throw small balls in) 40 small yellow balls or crumpled up pieces of yellow paper Oven mitts Safety Procedures Popcorn makers can release hot steam and get very hot. The kernels and popcorn can also get very hot. Be careful not to let students put face or hands near hot steam. Use an oven mitt to prevent burns. Engagement After presenting class objectives on Slide 2, ask students to recall middle school lessons comparing the size of the Earth (and other planets) to the size of the sun. Ask students to use analogies for how small we are compared to the sun. Ex., We look like a speck of dust ; We look like a marble next to a bowling ball, etc. Show students Slide 3 to confirm their analogies. Ask students to explain some of the important roles the sun has in the life of our planet (again, recalling M.S. standards). Show students Slide 4 of the PPT to transition to the popcorn experiment (Slide 5). Exploration 1. Have students gather in groups of 3-5 students. 2. Pass out small bowls with 2 tsp. of popcorn in each bowl. 3. Have students take turns weighing the bowl + popcorn on the digital scale and enter that information as indicated on their student guide. 4. As students wait, they should continue working on their student guides answering question #1 and/or discussing projected results. Solar Energy Green Box: Lesson 1 The Sun and its Core 4

5 5. Once students have completed weighing their bowls, ask students to take turns carefully popping the popcorn in the machine. Students should be making observations and completing guides during this process. 6. Post-popping, have students weigh the popped popcorn. 7. Once they have reported the data, students can eat the popcorn. 8. Show students Slides 6 & 7 and go over student responses as a group. 9. Go through Slides 8-15 with group to explore how nuclear fusion occurs. 10. Ask students to compare this process with the popcorn experiment and to complete question #4 & 5 in their Student Guide. Explanation 1. The sun is made up of what two main elements? 2. What conditions are needed for nuclear fusion to happen? 3. What was released during the process of nuclear fusion? 4. Did the total number of neutrons and protons stay the same during the process of nuclear fusion? 5. Can you compare this process to any other similar processes? Scientific Vocabulary: Atom: The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. Hydrogen: The electrically neutral atom contains a single positively charged proton and a single negatively charged electron. Hydrogen is unique in that it has three isotopes (each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties). Deuterium: Deuterium is one of the isotopes of hydrogen. It has one proton and one neutron. The most common isotope of hydrogen is protium, which has one proton and no neutrons. Because deuterium contains a neutron, it is more massive or heavier than protium, so it is sometimes called heavy hydrogen. Tritium: Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons. Helium: Helium is the second most abundant element in the universe after hydrogen. It contains two protons and two neutrons. Photon: Also called Light Quantum, is a minute energy packet of electromagnetic radiation. The term photon is from Greek phōs, phōtos, light. The energy of a photon depends on radiation frequency; there are photons of all energies from high-energy gamma- and X-rays, through visible Solar Energy Green Box: Lesson 1 The Sun and its Core 5

6 light, to low-energy infrared and radio waves. All photons travel at the speed of light. Nuclear Fusion: The union of atomic nuclei to form heavier nuclei resulting in the release of enormous quantities of energy when certain light elements unite. In the sun, helium is produced by the fusion of hydrogen atoms. Gamma-ray: Gamma-rays have the smallest wavelengths and the most energy of any wave in the electromagnetic spectrum. They are produced by the hottest and most energetic objects in the universe, such as neutron stars and pulsars, supernova explosions, and regions around black holes. Radiation: The process of emitting radiant energy in the form of waves or particles. Elaboration Become a Star Divide the class into group A & B. Give each student one crumpled up piece of yellow paper (this represents a photon). Have all students stand and tell them that right now they represent hydrogen atoms (protons). Have students recreate the process of fusion by pairing up with other hydrogen atoms (only from their group) creating deuterium (1+1), tritium (2 + 1) and finally helium (3+3, with the release of two protons to find more partners). As they pair up, one student from the pair releases a photon in the Group A or B bucket. Have extra photons available in case students run out. Whichever group has the most photons in the bucket after 10 minutes wins! Evaluation Formative: Qualitative Data Classroom participation assessed informally based on contribution to discussions, group work, and completion of Student Guide. Summative: Quantitative Data Students will complete and return the Student Guide to teacher for assessment. Rubric Complete definition of fusion: 25 Accurate description of how fusion occurs (proton-proton chain reaction): 25 Solar Energy Green Box: Lesson 1 The Sun and its Core 6

7 Popcorn activity connection to fusion: 25 Description of photon s impact on Earth: 10 Clean-up During the popcorn experiment students need to check their spaces to make sure no kernels, popcorn, or photons are left on the floor. Photons should all be placed back in the buckets for the Teacher to collect. Closure Review the final slide to recall lesson objectives. Ask students to explain the atomic reactions that occur in nuclear fusion and to explain what a photon is and how it is made. Ask students why this matters to them and to life on Earth as we know it. As part of the review ensure that students understand that nuclear fusion is a process where protons in atoms fuse due to extremely high pressure or gravitational force. This fusion releases photons. Photons (packets of energy) travel through radiation to the Earth. During their travel photons become other forms of energy including heat and light. The popcorn experiment is similar to process of fusion because the conditions of heat and pressure make the kernels pop and release energy in the form of steam, heat, and sound. The popcorn experiment is not like fusion because the kernels don t actually fuse to release energy. Adaptations for ESL, Special Ed, or G.T. Not applicable. Management Strategy In this lesson students will be involved in several collaborative learning exercises. This will require the teacher to design a classroom environment conducive to these activities. Students will be split up both small groups of 3-5 and into larger teams. Room must be made for the students to collaborate within the activity. The placement of the desks in a classroom is important in defining how the students will interact. The teacher should walk around the classroom when disseminating information to ensure that all students are engaged and receiving important information including safety and content. The teacher should also make sure that all students are able to see all visuals presented in class. By doing these things and providing relevant contexts for the content the students will remain engaged and behavioral problems will be reduced. Solar Energy Green Box: Lesson 1 The Sun and its Core 7

8 The popcorn maker, digital scale, and bucket placement is also key to safety. Planning should be done when conducting activities so that traffic jams do not occur in the classroom. Solar Energy Green Box: Lesson 1 The Sun and its Core 8