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Using Labs to Teach Physics/Chemistry

  1. Jun 9, 2010 #1
    I teach High School Chemistry and Physics in a low income area. I have grown to become a skeptic in the over all value in labs. I do see them as a way to mix up the class and make it more interesting from the perspective of changing up the scenery. However, I am not convinced that students learn as much from labs as much as other teaching methods. When I was in school I did not enjoy my chemistry labs because I felt like I already understood the concepts and doing a lab required less brain strain than the problem set, and therefore redundant. I know I am probably a minority here.

    However -- I would not feel the same about inquiry based labs. They are of great value, but they take a lot of time and devised in a paradigm that is contrary to the current mood of teaching to the test.

    What do you guys think about this?

    Regards,
    Chris Maness
     
  2. jcsd
  3. Jun 10, 2010 #2
    I took an introductory physics course in high school, and now (xxx years later) I am teaching college/university physics. I remember two things from my high school physics course: a brief discussion of relativity, and an experiment that was done in class (and I remember the experiment because I thought it was a very clever way to get data).

    The "hands-on" experimental approach offers several advantages. It forces students into active learning. In draws direct connections between theory and 'real-life' responses students can see. It allows students to make mistakes and try to find solutions on their own. (If this part is taught) it allows students to see the limits of measurement accuracy and the errors inherent in any measurement (Kills 99.999% of all germs on contact!!!). It provides an excellent platform for developing group work skills.

    Labs add to student understanding and concept recall by incorporating more sensory data. According to researcher Nick Van Dam (The eLearning Fieldbook, (c) 2003), students recall information and experience based on an inverted pyramid, with the smallest volume of recall (the point of the pyramid) representing what they read (NOTE: remember this, all teachers of online asynchronous classes !!!!). In order of increasing impact and recall are what students see, what students see and hear, and what students say or write. At the top of the diagram (base of the pyramid, representing the most effective method for recall) is what the students do.

    Whether all (or any) of your students will ever grow up to be wet chemists or bench lab physicists doesn't matter as much as the students understanding the scientific method and the limits inherent in any scientific claim. I have met too many people (student and adult) who are indiscriminate in their acceptance of dubious scientific-sounding "facts". If the lab does nothing more than innoculate your students from this, it will have served a worthwhile purpose.
     
  4. Jun 10, 2010 #3

    Andy Resnick

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    I think you are basically correct in your assessment, and I also agree with JazzFusion's comments.

    However, you haven't told us what you want students to get out of labs. What are your expectations? For the students to understand how GPS works? (good luck with that). Or could it be something simpler- an appreciation for the value of *data* in constructing theories and logical reasoning? The labs don't have to be overly contrived:

    http://www.sdbonline.org/index.php?Itemid=28&id=28&option=com_content&task=view [Broken]
    http://www.eskimo.com/~billb/edu.html


    You are correct that inquiry-based learning requires a huge amount of time on your part. Personally, I consider 'teaching to the test' to be counter to the spirit of learning (although at the K-12 level there are real pressures to conform- 'no child left behind' and all that...).

    You're in a tough situation, and I applaud your efforts to teach the kids real science!
     
    Last edited by a moderator: May 4, 2017
  5. Jun 11, 2010 #4

    Moonbear

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    As a practicing scientist, I would have to disagree that labs are not important. They are essential! I cringe when I hear of high schools that do not expose students to lab classes. Here's the catch...you can't design labs that always work. The best designed lab I ever experienced was one in which it was intentionally designed to disprove the hypothesis (this was a biology lab). Writing up a lab report about a "failed" experiment is worth its weight in gold in really driving home the lesson of what an hypothesis is and how to interpret results and draw a conclusion and write a quality discussion about it.

    One thing that a lot of scientists have in common is that they are tactile or kinesthetic learners. We don't really understand something until we get our hands into it.

    Labs should not just be "add chemical A to chemical B and watch the color change." There needs to be an hypothesis, predictions, experimental design, results, interpretation and conclusion. And there are experiments you can prepare that allow the students to develop the hypothesis and still do the same experiment whichever hypothesis they go with.

    For example, one we did in high school chemistry (sorry, I don't remember the actual reactions anymore, but I'm sure you could look it up) was to compare brand name and generic household products for amount of active ingredient. For example, you could ask your students to develop an hypothesis regarding whether a generic brand of bleach and a name brand are the same or different in their content of sodium hypochlorite. Either way they go with it, you're going to do the same analysis of sodium hypochlorite content. Then they will either support or disprove their hypothesis and have to write up a lab report discussing that. The other good thing about this approach is that each year, the hypothesis being tested is decided upon by that class, and is not going to be the same year to year, so they can't just pass along lab reports from one class to another.

    But this is a process. The first lab really might just be a gee whiz, look, we added clear chemical A to clear chemical B and the color changed from clear to pink, followed by a discussion of why properties of compounds are different from the reactants used to form them. This just gives them a chance to learn how to use the equipment, such as balances, test tubes, titration burets, being careful not to spill, etc. Then, you'll move on to some experiments where you give them the hypothesis, predictions being tested, and then they just get the results. Next step, you give them the hypothesis, but they list the predictions and are guided in designing an experiment. Last step is you let them form the hypothesis (in high school, you're going to pick experimental topics they can have opinions about...when they get to college we worry about them having to do a little more research about a subject before forming an hypothesis), predictions, etc.

    Not all of your students are going to become scientists. In fact, very few will. For those who don't, the labs will just be a break from boring problems or lectures, maybe no added benefit, but no harm done either. For those who have a spark of interest in science and may become a scientist, those labs are very important. Don't underestimate simply teaching them how to use a balance to weigh chemicals, or how to read the volume of a liquid in a graduated cylinder (accounting for the meniscus). These are minor but essential skills scientists use every day. But if you take it a step further and truly teach them to understand hypothesis testing, you will likely be the teacher they come back and thank years later for hooking them on science.
     
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