Designing Labs

I hated doing labs as an undergraduate.  I just wanted to finish as fast as possible, and I would take care of the thinking part later.  In retrospect, I suppose that this was mostly because I was a typical sleep-deprived college student, and labs were usually an exercise in tedium.  Everything that I had to do was laid out before me, and all that was required of me was to follow the steps.  The whole process reminds me a lot of this:

source

I have used boxed recipes to great effect in the past.  This recipe will in fact produce a super moist chocolate cake.  Will it turn me into a good baker, though?  Doubtful.  After repeating many cake recipes many times over, I will probably start to get an idea of the proper ratios of flour, milk, eggs, baking powder, etc., but what if I am out of eggs and need a substitute?

I believe that my duty as a science teacher is not to tell science to my students, but to show them what it is like to be a scientist.  How many of you scientists out there have ever been given the exact steps needed to solve a problem?  The idea sounds silly, yet that is exactly what we do with our students.  Worse yet, we often tell them the answer that they should get (i.e. the “accepted” value for the acceleration due to gravity is 9.8 m/s2), and then ask the students how close they got.  To me, this sends the message that not only is science merely a process of steps that they need to follow, but also that science is already done.

I want my students to feel like they are part of the scientific process.  I want to present them with a challenge for which they must devise their own solution process.  I want my students to feel like their results are meaningful (not inferior because they didn’t get the “accepted” value).  Now, I’m not going to leave the students completely out to dry; clearly, some experiments are complicated enough that some guidance is necessary.  But I believe that some struggle is good.  In fact, an international survey of teaching techniques showed that the countries with the highest math and science achievement allow their students to struggle instead of telling them the steps they need to know (see Michael Pershan’s What if Khan Academy was made in Japan?).

So this is what I want to try this term: each lab handout will consist of a short statement outlining the goal of the lab, and I will also list the materials that are available to them.  That’s it.  If necessary, I will provide some ideas, but I think at the very least students should have control over the number of measurements they make, what particular values they use, etc.  Here is an example:

Goal: Determine the relationship between electric field strength and distance from a charged particle.  (That is physics speak for “Construct an equation that has electric field strength and distance as the only two variables”.)  Your measurements and final equation should include units and uncertainties.

Materials: You will use a simulation applet that you can find at http://phet.colorado.edu/en/simulation/charges-and-fields.  Data entry and analysis will be done using a program called LinReg.

I’m interested to see what the students think of this style of lab.  I have experimented with it before when I asked students to determine the relationship between drag force and speed for a falling coffee filter, and they really seemed to like the freedom that they had.  My hope is that by doing this kind of lab repeatedly, my students will get better at the process of designing an experiment and interpreting the results.

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One thought on “Designing Labs

  1. […] models, then use lab time to “prove” that those ideas were correct.  In addition to other reasons I dislike those kinds of labs, they are not a valuable use of time. Using lab time to develop those very same models, though, […]

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