One Reason to Give Presentations

I really enjoy giving presentations to other educators, it's probably related to why I love being a teacher. The major difference is that when I present to my colleagues they generally want to learn what I'm trying to teach and this makes it even more fun. This is not why I'm writing today. I'm writing today because I just had an epiphany. I discovered another reason to love giving presentations.

My new thought came while preparation to lead a workshop in the use of video analysis in teaching. It's going to be a six hour long workshop.* Originally I was mainly going to focus on the how, but with six hours I have more than enough time to present the why as well. It was while getting these thoughts in order that the light bulb went on.

I have to think of well reasoned justifiable reasons to present to other physics teachers to convince them to try what I'm teaching. Do I have them? Is there research to support them? Or is it all just fluff and hand waving meant to grab attention. I have reasons, but I'm not an educational researcher, but physics education is one area where there is lots of research, so I've been told. So I went to the internet and my bookshelf.** It turns out, that according to research, my gut feelings were right. I'm not totally surprised by this as I go to lots of meetings and talk with lots of people. All of these interactions added to my own classroom experience have led to my "gut feelings".

Anyway, I'm not writing to say, "Woo, Hoo I was Right!" I'm writing because the process of researching and thinking about justifying the power behind the programs and approaches I will present has caused me to think of about half a dozen new labs and/or demos I can use in my own classroom.*** These will get written up for my presentation and will go into my ever expanding bag of tricks to use.

While writing this I just realized what I'm doing when I prepare a presentation. I reflect on my teaching. Back in ed-college "they" often talked about the power of reflection. Unfortunately I don't carve out enough time to do this, but in preparing to lead workshops or presentations I have to make the time.

*It will be run SE Michigan in the spring of 2010. Let me know if you want more information.

**My physics teacher mentor left me all his books when he retired.

***Damn that's a long sentence. I wonder if it's grammatically correct

Demo of Ohm's Law

As a member of two different local physics groups, DMAPT and the MIAAPT, I get to meet lots of great teachers and more importantly I get to see their best demos. The demo/lab below is not one I actually saw presented, but one I read about in a lab manual written by Dr. Paul Zitzewitz (who recently retired from the University of Michigan, Dearborn). Paul sent me a copy of it so I could mine it for ideas to use in my own teaching.

Ohm's Law is one of those tough ideas to truly understand. The math is pretty easy, but what are voltage, current and resistance really? You can't see them and you can't put your hands on them and so many students never really understand the underlying concepts.

In Paul's lab manual he builds an analogy between electricity and blowing through straws. The straws serve as the resistors. You can use different sizes to represent different resistance values. The pressure you blow with is the potential difference (voltage), and the rate the air flows is current. You can easily extend the analogy by putting multiple straws in series or parallel and "measuring" the effect on current.

Full Length Mirrors

I saw this demo at last summer's (2009) meeting of the American Association of Physics Teachers. It was part of a really great presentation by Dr. Peter Hopkinson. The basic question was, "How large does a mirror need to be to see your whole body?" The concensus response from the audience of physics teachers was, "It depends on how far away you are from the mirror." As it turns out, the wisdom of crowds failed this one.

I managed to score a "full length" mirror from Target for $5. The mirror is one of those cheap ones you put on the back of a door and is nowhere near my height, it's about 2/3 my height. Yet if I mount it appropriately I can see my whole body at any distance. Just watch the video below for full details. Oh, and if you ever get a chance to see Dr. Hopkinson speak at a meeting you should jump at it!