Some thoughts about teaching (mostly addressed to my students).

Here are some points about my teaching style and the organization of the course to help you understand what I am doing in my courses.

I don't lecture much, here are some reasons why:

• Suppose went to the track coach and said you wanted to learn how to pole vault. All of the following might be helpful but which do you think might be most useful in teaching you how to pole vault?

• Watching a film about pole vaulting.
•  Reading a book about pole vaulting.
• Having the coach describe to you how to pole vault.
• Having the coach demonstrate how to pole vault.
• You picking up the pole and practice trying to pole vault with the coach acting as an advisor, telling you what you are doing wrong.

Although you may fall on your face a few times, I'm pretty sure the last method would produce the quickest results. The same with physics; practicing on problems and having the instructor bail you out when you get stuck or make mistakes is the most productive way to learn physics.

• The book is a better set of lecture notes than anything I can give you in class. In fact, the way most text books are created is that an instructor makes a very careful set of notes, corrects them over a couple semesters, adds problems and has it published. By the time I write something on the board and you copy it down, it is bound to have more mistakes than the book. The book can also give you many more examples than I can in the short class time we have together.

 
• Suppose you were taking a literature class on Shakespeare and were studying Macbeth. It would be a pretty lousy class if all the instructor did was come to class and read Macbeth to you. You would get a lot more out of a class if you came having read the play and the instructor asked students in the class to react to questions about the play or had the students ask questions about parts they didn't understand. That's what I'm doing in class; I assume you have tried reading the text and class time is to be spent on me asking you questions and you asking me questions about the material, not me repeating what is in your book.

 
• The education research literature shows that using collaborative group problem solving and other interactive methods in a physics class can raise the average scores by as much as 30% on standardized tests compared to classes taught with a straight lecture method. This has been verified at many schools, with many instructors, with many different class sizes and types of students. It is hard to argue with these facts...

The following summarizes the results of a 6000 student study comparing classes (high school, college and university) that used interactive methods and those that did not (labeled traditional in the graph). Note that whatever the pre score was (high for students with strong backgrounds, low for high school novices), the gain from pre to post was higher for interactive methods.

Some comments about Labs.

• Labs are often ahead of the course material. This is intentional. Education research shows that you learn a lot more if you see the physical problem before you read about the theory. If you think you know what is going to happen you often miss important aspects of what is really going on. So usually we will do the lab ahead of the course; normally only by a week or so if we are lucky. You are free, however, when writing your lab reports to look ahead in the book to see what the theory says.

 
• Some labs use old equipment which increases the error of the results. This also is intentional. No experiment ever done in the history of science was/is100% accurate. One of the most important thing to learn about doing an experiment in science is to learn how to isolate the error inherent in the equipment from possible deviations of experimental results from theory. It is doubtful that you will disprove any laws of physics in the labs you do in my course. So the emphasis in these labs is in being able to estimate how much error you expect to have given the equipment or; under the best conditions with this equipment, what is the worst your answer could be off by?

 
• The labs don't have a step by step set of instructions, which is also intentional. The object of the exercise is not to see if you can follow a recipe (that would be a cooking class). The directions are designed to make you think about what you are doing and so are purposely not too detailed (but if you get stuck be sure to ask the instructor- that is what we are here for).

What is wrong with using Google or Wikepedia, etc.?

Suppose you have the following question in your book:"Tas ir jautājums, lūdzu, atrast atbildi." You are not real sure what is being asked so you go to Google and you type in the question and you get the following answer: "Šī ir atbilde uz jautājumu. Es atklāju, ka par google." You cut and paste this into your paper and turn it in. It is the correct answer. Should you get credit for it? Unless you read Latvian, probably not. You didn't understand the question or the answer. Sure, you found the correct answer but you didn't understand what you were doing. Learning means understanding what you are reading and being able to explain it in your own words. As an instructor, I have no way of knowing that you actually understood what you found if all you did was copy and paste. I need to read your explanation in your words to know if you learned anything.

A second problem with the Internet is deciding if a site is reliable or not. Is a document titled 'A Scientific Perspective on the Cigarette Controversy' likely to be biased against or for the tobacco industry? Are the published results from a conference on climate change titled 'Restoring the Scientific Method' reliable? Sounds good (has the words Science and Scientific in them). But are they? Turns out, the first report was sponsored by the tobacco industry and the second by the coal lobby. So you might want to read something a little less biased. How in-depth do you have to search to find out (as Naomi Oreskes and Eric M. Conway did in Merchants of Doubt; How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming) that the Marshall Institute, the Competitive Enterprise Institute and the Heritage Foundation were all started by the same handful of people and so represent basically the same point of view? If you did not stop to investigate their connections with each other you might assume you were reading three independent groups of scholars who happen to agree. What looks like a consensus of independent experts is actually a consortium of the same viewpoint in this case.

A third problem in using Internet sources is concerned with how we find things on the Internet. We now know from Eli Pariser's book The Filter Bubble: What the Internet Is Hiding from You that most search engines (Google, Amazon, Yahoo, etc.) are personalized to the individual user. This is done by tracking which links you click on in a search and in some cases by looking for key words in your email. Your past Internet use skews your future searches so that you cannot be sure you have adequately researched a topic. In doing research for my book, Foundations of Environmental Physics, I did a significant amount of investigation of climate skeptics. Gradually my Amazon and Google searches shifted to put climate skeptic books and links at the top of the results. Had I not realized what was going on I might have concluded that there were more anti-climate change sties and books than links and books in support of human caused climate change. Since then (about a year ago) my searches about climate have gradually shifted back to more recognized scientific links such as NASA and NOA, again showing my preferences in sources.

The point here is, THINK about what you see on the Internet. As my grandmother use to say, "Don't believe anything you hear and only half of what you see." Check out the sources of the information you read. Look to recognized authorities for information. Compare sources. And think about what they say, don't just copy it down.

Here are some references.

• I. Halloun and D. Hestenes, 'The initial knowledge state of college physics students', Am. J. Phys. 53, (1985) p1043
• L. McDermott, ìMillikan Lecture 1990: 'What we teach and what is learned: Closing the gap', Am. J. Phys. 63, (1991) p301.
• D. Hestenes, M. Wells, and G. Swackhamer, 'Force Concept Inventory', Phys. Teach. 30, (1992) p 141.
• P. Heller, R. Keith, S. Anderson, 'Teaching problem solving through cooperative grouping. Part 1&2' Am. J. Phys. 60, (1992) p 627.
• D. Hestenes and M. Wells, 'A Mechanics Baseline Test', Phys. Teach.30, (1992) p 159.
• R.J. Beichner, 'Testing student interpretation of kinematics graphs', Am. J. Phys. 62, (1994) p 750.
• E. Mazur, 'Peer Instruction: A Userís Manual', Prentice Hall (1997).
• A. B. Arons, 'Teaching Introductory Physics', John Wiley and Sons (1997).
•  D.R. Sokoloff and R.K. Thornton, 'Using Interactive Lecture Demonstrations to Create an Active Learning Environment', Phys.Teach. 35, (1997) p 340.
• C. E. Swartz, T. Miner, 'Teaching Introductory Phyics; A Sourcebook', American Institute of Physics (1997).
• R.R. Hake,'Interactive-engagement vs traditional methods: A six-thousand-student survey of mechanics test data for introductory physics courses', Am. J. Phys., Jan. (1998 ) and on the Web at <http://www.physics.indiana.edu/~hake/index.html>; see also <http://www.aahe.org/hake.htm>.
• D. Hestenes, 'Who needs physics education research!?', Am. J. Phys. 66, (1998) p465.
• Karen Schilling 'Expectations in the classroom: Are they too low?' AAC&U Peer Review, Fall, 1998.