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23 February 2011

How I "conduct" a laboratory session -- NO HANDOUTS!

But Mr. Lipshutz, you didn't tell us
 which graduated cylinder to use!
At my AP summer institutes, I offer attendees my entire general and AP physics laboratory program.  I describe each experiment briefly in writing; I include the "lab report" evaluative exercise that is assigned for homework; and we even actually conduct three of the labs I use.

Confusion generally reigns, though, until teachers actually try out a couple of my experiments.  The issue?  "What do you give to the students so they'll know what to do?  Do you have the lab handout?"

My answer is, I give the students nothing.  I demonstrate the use of the equipment -- moreso early in the year than later in the year.  I tell the class what to measure and how to measure it.  On the board, I draw the graph (always a graph) that they should make.  That's it.*

But how will the class know what to do? 

First of all, they LISTEN to me.  If they know a handout is coming, why should they listen actively to anything I say?  "I'll just read the handout," they'll think.

Secondly, I don't want students blindly following directions.  Figuring out how to measure something is an experimental physics skill, even at the most basic level of "how are we going to find the volume of this water?"  Recognizing that they need a graduated cylinder rather than a beaker, then selecting an appropriate cylinder from the shelf, then realizing that the one they chose was too big -- all that is a learning experience.  My placing the proper-sized cylinder on the lab table and writing "pour the water into the graduated cylinder and read from the bottom of the meniscus" teaches the class to follow directions, nothing more.

And finally... how many times have you handed out a carefully-prepared lab sheet, then had ten students ask a question to which the response is, "Look at the handout here."?  Students DON'T READ LAB HANDOUTS CAREFULLY.  We all know this.  So instead of wasting time preparing a handout, then getting frustrated, then complaining about how these dang kids today don't read anything... just don't give a handout.  Laboratory isn't the time to be teaching the skill of following written directions, I don't think -- that's for homework, tests, and home ec class.

I know you're skeptical.  After all, your teachers all through high school and college probably never failed to hand out a lab sheet with complete instructions.  It's not easy to let go of this crutch.  But flying by the seat of your students' pants in lab does work beautifully.  Joshua Beck, who attended my workshop at NC State University last summer, says not giving a procedural handout on lab days "has been great, for me and them."  He's right.  Try it.

* Sure, early in the year I make sure everyone is acquainted with my lab requirements, as shown here.  These aren't on a handout, they're just oft-repeated guidelines. 


  1. This is great, I love it. I teach in a program intended for science teachers who want a physics license. The labs I do are a lot like this and they struggle with them. It's great to teach teachers, though, as we often take time to discuss the strengths and weaknesses of the labs.

    On the other hand I haven't had much success convincing my department to do the same in our normal general physics labs. For the moment they're pretty cook book but I'll keep working.

  2. Nice idea. No more wasted paper or time!

  3. I often ask students to make several graphs and data table columns to aid in their analysis, for example, in a spring lab plotting the square of the period vs the mass or the log of the period vs the log of the mass. Do you do these kind of things? Do the students only plot their raw data as they go?

    I guess my question is more about open-ended labs with little instruction rather than labs with explicit instructions that are oral. I find I need to specifically draw attention to the meaning of slopes, to what would linearize data, etc. How do I promote this without a sheet that explicitly asks for it? Thanks!

  4. MPT, this might be a whole post eventually -- I understand your question. Send me an email, and I can send you a file of the "lab writeups" which *do* ask for the meaning of slopes of linearized data. But instructing the class on what to collect, what graph to make, and how to linearize the data is all done orally.

    I do not ask for data tables; those get made without my advice, and are not important to the results. I do tell the class *after* data is collected what to do to linearize. Students do only plot raw data as they go, they linearize later. I think of the lab writeup, which is done for homework after lab, as a way for students to communicate that they understood the instruction that went on during lab, or as a way to force students to ask questions where they don't understand.

  5. nice, whatever way you choose, it should keep the attendees engaged.