Demos

  • Demo basics:
    • Demos are a great addition to a standard/dry worksheet.
    • Sometimes they actually do help elucidate concepts and students like doing “hands-on” experiments (this is a science class!).
    • As always, the EBRB is a great resource and has a page devoted to demos.
    • In addition, on a given topic's page in the EBRB, there should be listed any relevant demos.
  • What makes a good demo?
    • Illustrating difficult physical concept(s)
    • Interactive: students can participate
    • A springboard to new topics
    • Straightforward: minimal risk of failure
    • Demo actually illustrates concept in question
  • When demos go wrong:
    • Demos can and sometimes do FAIL!
    • Sometimes, especially in astronomy, they can confuse students more than help them or oversimplify a concept.
    • Materials may be missing or broken, so CHECK IN ADVANCE!
  • Some of our favorite demos:
    • Remind everyone that most are written up in the EBRB and on the Resources handout (and wiki page)
    1. Arc lamps: Put high voltage through tubes of gas and look through diffraction gratings to see spectral lines. On the EBRB Light Blackbodies Spectral Lines and the Doppler Effect page, “under Line spectroscopy and arc lamp activities”.
      • Head GSIs will train GSIs, Ask Ay375 instructors if you need help.
      • Students like this one
      • Make sure the stuff is there if your section is early in the day.
      • Test it yourself and make sure you can see lines so you can help your students better.
    2. Warping of Spacetime: A 2D analogy using stretchy black fabric and balls/weights. No worksheets exist in the EBRB for this one, but feel free to make one!
    3. Celestial sphere, phases of the moon, seasons, orbits: Styrofoam balls, a lamp or flashlight, people getting up and moving around. Many worksheets go with these kinds of demos and can be found on the Demos page of the EBRB or on the Celestial Sphere, Gravity and Orbits, and Earth/Moon/Sun System pages of the EBRB.
      1. Retrograde motion (Discuss pitfalls)
      2. Day & night on Earth (circle up around a lamp and groups of 3)
      3. Lunar phases (balls on a sticks around a lamp and groups of 3)
      4. Seasons (circle up around a lamp)
      5. Lunar rotation and orbit (i.e. tidal locking) (one person orbits another with the Moon's arms outstretched)
    4. Parallax with your finger (very simple, “close one eye then the other” kind of thing)
    5. Doppler shift of sound (whirling a buzzer on a string)
    6. Class H-R diagram
    7. Stating in words, stating in math, drawing, and acting out Kepler's and/or Newton's Laws (can be done with a worksheet, or just have students take notes as each group presents their law)
    8. Donut/bagel on a string (though I'm sure profs will do it in class)
    9. Jumping on a chair with balls being thrown (though I'm sure profs will do it in class)
    10. (Rayleigh) Scattering of Light: Fill a fish tank with water and a couple drops of milk and shine a flashlight through it to show scattering of blue light and transmission of red light. On the EBRB Light Blackbodies Spectral Lines and the Doppler Effect page there's a worksheet called “Emission, Absorption, Scattering, and Nebulae” and one called “Scattering Demo.”
    11. Planetary Nebulae (and Limb Brightening and Optical Depth): use a Hoberman sphere covered in Christmas lights to show how spherical radiating clouds can appear ring-like. On the EBRB's Stellar Evolution page, there's a worksheet called 'Limb Brightening: “Hoberman Planetary Nebula” Demo.'
    • Physics has some, but it's kind of a pain to check them out, but some are good for section and some are good for full lecture.

Trace: • demoshandout