AY 375 - Fall 2017: fourth Day Lesson Plan

Today we'll be discussing two somewhat disparate topics, how to incorporate demos into a lesson plan and how to write good multiple choice and free response questions.

1. Deeper conceptual knowledge CAN be probed with multiple choice questions, but writing effective questions takes time and practice.
2. Especially when writing free response questions, it can be useful to develop a grading rubric for each question as a way of ensuring that your questions are specific, clear, and not testing the same concept over and over again.

First have students discuss in pairs how section went (5 min).

Open the floor up for general questions and sharing about how sections are going. Some questions include:

• What did you do?
• How did you implement your activities?
• What worked?
• What didn't work?
• What would you do differently?
• How did you assess learning?
• Did you receive any unexpected questions/reactions/etc.?
• Did anything unexpected happen?
• What were you thinking about while you were running section? Any moments of panic?

Printable Version Here: DemosHandout

• 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.

1. (20-25 min) Go through question example slides as a class exercise.

Some notes on multiple choice questions:

Despite their outward appearance, these questions are actually inherently nonobjective. Grading an essay exam is subjective to the personal feelings of the grader, compared to running a Scantron through a machine. Grading written problems falls somewhere between the two. This is only partially correct, “grading” a Scantron is completely objective, but the subjective aspect of multiple choice questions comes in the creation of the item (the question), the response (the correct answer), and the distractors (the incorrect choices). If everyone in the class was to write a question about the Doppler Effect, we would see a range of different questions and a range of ideas probed. That is subjective.

The ultimate goal of testing is to measure what the students actually understand, and the process of interpreting the meaning of a student's response to a MC test is a subjective one. There are three major issues behind writing these sort of questions:

1. the physical format and layout of the question
2. the conceptual hierarchy of the questions
3. the statistical item analysis

Below are some guidelines for each of these items.

You are testing the students' understanding, not their reading ability. Long passages of text cause slow readers to skim and often miss details. Questions should not include strings of prepositions, parenthetical statements, or extended clarifications. Misinterpretation is impossible to completely predict, but concise, clear questions can do a lot to minimize the chance of students misreading the question or the response. For example,

You forget that the star Betelgeuse is a red giant and apply the method of magnitudes to determine its distance. The true distance to Betelgeuse is actually… (a) shorter than you calculated, (b) the same distance that you previously calculated, © farther than you calculated.

Is short, to the point, and clear. You might be tempted to elaborate on small points that are not the main conceptual item that is being tested, but care must be taken. For example,

You forget that the star Betelgeuse is a red giant (a very luminous star in the top right of the HR diagram with relatively low surface temperature) and apply the method of spectroscopic parallax—a comparison of the star's apparent magnitude, estimated from the HR diagram, and its absolute magnitude—to determine its distance from Earth, which can be considered the sam as its distance to the Sun because the Earth-Sun distance is negligible given the scales involved. The true distance from Earth to Betelgeuse is actually…

In an attempt to be completely clear, the stem has become more difficult for most students to understand!

Over the years, students have learned that when novice faculty includes choices such as “all of the above”, these are frequently the correct answer. It's easier as a test writer to write correct statements than to come up with plausible sounding incorrect statements. Also, students have also learned that the longer answers are usually the correct answers. You can avoid these situations by making sure your choices are all of similar length, contain a similar amount of scientific vocabulary, and ensure that an equal number of choices (A), (B), etc. are correct on the overall test.

Consider

The thermo nuclear reactions in a stellar core are the result of (A) fission, (B) fusion.

This tests what? Unfortunately, it tests word association. A student can get by without knowing what fusion means. Students learn to adopt a strategy of memorizing definitions and words, rather than understanding concepts. As another example,

The Monotillation of Traxoline (attributed to Judy Lanier) It is very important that you learn about traxoline. Traxoline is a new form of zionter. It is monotilled in Ceristanna. The Ceristannians gristerlate large amounts of fevon and then bracter it to quasel traxoline. Traxoline may well be one of our most lukized snezlaus in the future because of our zionter lescelidge.

Directions: Answer the following questions in complete sentences. Be sure to use your best handwriting. (1.) What is traxoline? (2.) Where is traxoline monotilled? (3.) How is traxoline quaselled? (4.) Why is it important to know about traxoline?

Notice how easy it is to get 100% without understanding a single thing about the passage! Pay attention to wording.

Less applicable for GSIs, but if particular questions are frequently missed, it is necessary to probe whether they are missed because of a lack of clarity, or because the question is testing difficult concepts. If the former, revise!

See below for some general bullet points on what to look out for.

Some notes on free response questions:

These notes are written with “Astro C10 quizzes” in mind, but the ideas are generally applicable.

• These points are valid for both quizzes and exams:
  • Test the material emphasized - Exams should reflect the fact that students should know the big concepts really well, as opposed to knowing a bunch of smaller concepts only peripherally.
  • Keep questions short and to the point - Students should spend the majority of their test time thinking and answering/writing, NOT reading.
  • Edit questions for clarity - Clear questions tend to be shorter and if anything is ambiguous it confuses and slows down students and makes it harder for you to grade it fairly. Have someone else take your exam to give some feedback. If you're taking an exam for someone else, be critical and think about possible ambiguities.
  • Don't write a long test - Keep it concise, to the point, and clear! The rule of thumb is your average student will take double or triple the time it takes a GSI to complete the exam. Also, 90% of your students should finish the exam completely in the allotted time.
• Quizzes vs. Homeworks
  • They're quite similar in their construction and type of questions.
  • The main difference is that quizzes should be shorter and have easier questions, since students have much less time to work on quizzes and must work on them alone.
• Quizzes are:
  • short
  • usually given in section
  • questions are of exam difficulty (i.e. easier than homework questions)
  • Not too in-depth or calculation-based. Some light calculation might be OK, but take care. (Not everyone will remember a calculator no matter how many times you remind them, and many people will be petrified of the idea of computing things on their own.)
  • usually only cover recent material (i.e. the past 2-3 weeks)
• Quizzes are used:
  • by the GSI to gauge each students' understanding of recent material individually (as opposed to homeworks which can be done in groups)
  • by the student to gauge their own understanding of recent material and get a feel for what a college level intro science course non-Scantron exam will look like and what level of understanding they are expected to have for the exams
  • by the prof to get a grade early in the semester that's more important than a single homework, but isn't the big production that an exam is (you might not have covered enough material for a full exam)
• What makes good ones?
  • not too long (both in length of individual questions and number of questions)
  • not too hard
  • not too easy (shoot for a variety of difficulties in questions)
  • relevant to recent material
  • varied in the types of questions (multiple choice, fill in the blank, calculation/mathematical, read a graph, free/paragraph response)
  • unambiguous with easy-to-read questions
  • not mathematically demanding - questions should probably not require a calculator and should definitely not include extensive tedious calculations
  • representative of same knowledge required for exams
  • gradable for partial credit (not simply binary right/wrong like Scantron exams)
  • specific about what you're looking for in free response type questions: Don't give students the opportunity to 'core-dump' for a problem, it wastes their time spewing forth useless information and makes your life tougher when you have to grade the mess.
  • quick to grade (this makes your life much easier and helps the grading be more fair for all of your students)
• Quizzes are meant to be relatively low stress (especially compared to full exams)

General notes from previous years in convenient bullet-point form:

• Exams exist to:
  • Evaluate student learning for University-required grading
  • Motivate students to study and understand the material
  • Allow the instructor to evaluate his/her progress educating students about the material
  • Provide feedback to students about their understanding and study habits and illustrate specific gaps in their understanding of the material

• What makes good multiple choice exam questions?
  • Not too long/wordy (neither the question nor the possible answers)
  • Not too much calculation
  • Not too tricky (i.e. there shouldn't be two extremely similar answers)
  • Relevant to important material (as opposed to really obscure/minute details)
  • Very clearly written, precise wording in both question and answers
    • E.g., 'Which best describes…' as opposed to 'What is…' or 'How does…happen'
  • Pedagogical as well as evaluative (e.g., some questions should probe common misconceptions)
  • Questions that are very easy or very difficult are OK as long as the test has questions with a variety of difficulties

• What makes bad ones?
  • Long answers!
  • Excessive use of 'all of the above' (some people say any use of 'all/none of the above' is a bad thing)
  • Questions that can be solved without knowledge of the material (usually because of the use of too many blatantly wrong or “funny” possible answers)
  • Multiple potentially correct answers (usually from vague questions or possible answers)

• Non-multiple choice questions
  • Types of questions:
    • Matching
    • Fill-in-the-table/blank
    • Simple calculations
    • Short answers and paragraph/free responses
    • Diagrams, plots, graphs
  • Most of the same points discussed above apply here:
    • Questions should be clear, easy to read, and unambiguous
    • Questions should be relevant to the material presented and emphasized (do not test on obscure passages of the textbook)
    • For high-value questions, allow for partial credit
    • Make the questions easy to grade! Don't give students the opportunity to 'core-dump' for a problem: be very specific about what you're looking for in these questions.
  • Can be more time-consuming than MC questions, depending on the overall length of the exam.