Welcome to Stars, Galaxies, & Cosmology

Transcription

1 Welcome to Stars, Galaxies, & Cosmology As you come in, please: Pick up handouts & sit toward middle of classroom. Complete info sheet and start diagnostic test.

2 You Are Here

3 A Widely Believed Incorrect Model of Teaching and Learning Bill Watterson

4 from How People Learn Students enter your lecture hall with preconceptions about how the world works. If their initial understanding is not engaged, they may fail to grasp the new concepts and information that are taught, or they may learn them for the purposes of a test but revert to their preconceptions outside the classroom. HOW PEOPLE LEARN, National Research Council, National Academy Press, 2000

5 Just-in-Time Teaching: A Research-Validated Teaching Strategy The Feedback Loop: Students respond electronically to assignments due shortly before class, and the instructor reads the student submissions "just-intime" to adjust the classroom lesson to suit the students' needs. ( For this to work, you have to try to learn the material on your own first. I have constructed a system to reward you for initial effort and also give you credit for learning and fixing your work. M.C. Escher I ll seek your input at the time of the first midterm to improve the feedback loop.

6 Key results from cognitive science and education research 1. Knowledge is associative: it is linked to prior mental models and formal structures 2. Learning involves production/construction: it requires mental effort 3. Most people require social interactions in order to learn effectively

7 Think-Pair-Share Which of the following statements is false? A) The professor may disagree with the textbook; it is not a perfect guide to the course or exams. B) If prep homework is not ed in pdfform by 9am on class day, it receives a zero regardless of the reason, but that zero may be one of four scores dropped. C) If you retype your prep homework when you correct it, the grader will appreciate that. D) You should save your voting card and use it all semester.

8 Peer Learning Peer learning is group work in which each group member is responsible for everyone s learning, with a peer leaderfacilitating the discussion. A peer leader facilitates Q&A and critical thinking in the discussion and does not lecture. This person is not expected to act as a teacher, but as a more advanced learner. Astro301 students will learn/review certain concepts during office hour problem-solving sessions that Astro102 students will learn in a more conceptual/less mathematical context. Astro301 students will cement their conceptual understanding via peer leading in class, enabling deeper concept learning for both Astro 301 and Astro 102 students.

9 Example: Frequency & Wavelength of Light Work with your group to reconstruct the equation relating the frequency ν and wavelength λ of light. Use unit analysis to check that you have the equation right, where the units of ν are Hz (=1/sec). Then read & answer the question below. A student says to you This equation tells me that the higher the frequency ν, the greater the wave speed c. Since visible light has a higher frequency than radio waves, that means visible light travels faster than radio waves. Which is true? A)The student is correct because visible light travels faster than sound (for example lightning and thunder). B)The student is correct because the speed of light is only constant between reference frames, not between frequencies. C)The student would be correct but the equationdoes not apply to radio waves. D) The student is incorrect because the wavelength changes so that radio and visible light waves travel at the same speed.

10 Back to where we started You Are Here Goals for today: 0. Review c=λν and the constant, finite speed of light. 1. Describe the Earth s location in the hierarchy of astronomical structures, and say what they consist of. 2. Remember what a light year is (and isn t). 3. Use powers of ten notation to relate the size scales of different structures.

11 Zooming in Henbest & Couper 1994 The fact that the Sun lies in a bubble of thin hot gas makes it easier to see stars. Perhaps we should thank the Local Bubble for the existence of astronomy on Earth

12 What is a light year? Light Year (LY) = distance light travels in one year Confusing! Not a unit of time! Dirty Little Secret: LY used only by educators! Real astronomers use parsecs (pc), or kpc, Mpc, etc. Like yards and feet pc bigger than LY by a factor of ~3.3

13 Think-Pair-Share In the original Star Wars movie, Han Solo says to Obi-Wan Kenobi, You've never heard of the Millennium Falcon? She's the ship that made the Kessel Run in less than 12 parsecs. She's fast enough for you, old man. What's the cargo? What is wrong with Han Solo s statement? Pick the word that should be changed (to what?): A) less B) parsecs C) fast

14 The Universe loves powers of 10! Watch and discuss the movie at: java/scienceopticsu/powersof10/ On your own time, you may also want to check out Richard Powell s Atlas of the Universe (

15 Think-Pair-Share Match one description to each structure: A.contains the Andromeda Galaxy B.region of thin hot gas containing well-known stars C.made of stars and gas arranged in spiral arms D.consists of planets around a star 1. The Local Bubble 2. The Local Group 3. The Milky Way 4. The Solar System 5. The Universe

16 Pencil & Paper Problem Consider the Earth and the Solar System. The Earth has diameter 10 7 m and the Solar System has diameter m. Using powers of ten, how many times larger is the Solar System than the Earth? In this question, is there a word that is not specific enough, and why?

17 Some closing words of wisdom from Monty Python Check out the Galaxy Song on youtube: