physicslab

Revamping Undergraduate Introductory Physics Laboratory

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This is a compilation of my blog entry on this singular “project” to change the way we conduct the introductory physics laboratory in most US universities. I think we are missing a tremendous opportunity to educate a general audience on how we acquire and learn something in physics, and how we analyze something that we don’t quite understand. To me, the ability to have such skills is extremely important, and transcends beyond just physics but into our everyday lives, since we have to make decisions all the time based on what we believe to be true.

Needless to say, this is an ongoing project. This document will be updated as more of my thought are put down into words.

Part 1

I used to hate doing the lab in First Year college intro physics classes. It would be 2 hours of torture, and at that time, I didn’t see the point. Unless things have changed, most students taking such classes would tend to feel the same way as I did. And I think this is a waste of opportunity to really get through to the students of THE most important aspect of science, and of physics in particular – the empirical testing of physical concepts, and how we arrive at our knowledge to accept something as valid. This is what separates science from pseudosciences (and even religion).

The problem here starts from the very beginning. When I was that freshman undergraduate, no instructor ever spent time explaining why the laboratory sessions are important, why it is crucial that we actually DO things, rather than just read or watch what is being done. No one was explaining to me the fact that the SKILLS that I could get out of the physics lab may turn out to be a rather important aspect of my education that transcends beyond just physics, but into other parts of my life. This means that it doesn’t matter if you’re a physics major or not, the physics labs can be quite beneficial as one progresses in one’s education, career, and life. I strongly believe students should be made aware of this in no uncertain terms. The physics instructors must impress upon the students why doing these laboratory experiments is important, what kind of skills are being practiced, and why this is different than just sitting and reading. I would think that the students would at least become aware that there is a rational reason for forcing them to do such a thing, rather than just them being told that they need to do this for no valid reason.

When I was a lab TA years ago, I tried doing just the very thing. More than 3/4 of my students at that time were not physics majors, and I flat out told them that in the lab sessions, it was more important to pay attention to what they were doing, and reporting what they were doing, rather than the final “answer” or results that they were trying to measure. I was more interested in what they were thinking as they were doing the experiment, reporting accurately their observations, and if the results looked weird, to notice that they did look weird rather than just reporting the number and did not realize something was not quite right. In other words, I was more interesting in the doing of the experiments themselves rather than testing if the students understood the physics theory or idea that was being tested. I was more interested that the student acquire proper experimental skills. They can learn more effectively about the theory and principles in class. I wanted the lab session to be more “hands on” on how to think and conduct an experiment to measure something.

So already my philosophy in what an intro physics lab session should be was different than what I encountered during my undergraduate years. And after being in this profession for many years, and being an experimentalist, I am even more convinced that this is what such lab sessions should be.

Part 2

So what is the main purpose of intro physics laboratory?

Keep in mind that MOST students in such courses are NOT physics majors. In fact, for many, these are the only physics courses they’ll ever take. So I see it as the best opportunity to introduce to the students how physics actually work. How exactly do we consider something to be valid in physics? After all, anyone and everyone can come up with some “theory” to describe something (and in the age of the internet, everyone does!). How do we select which ones are valid and which ones aren’t? It all comes down to experimental verification. How we know something to be valid come from our empirical observations. Therefore, proper experimental techniques must be crucial since it can determine what is valid and what isn’t. This is where the acquired skills come in.

When I say “skills”, I don’t just mean physical skills, such as the efficient way of using an oscilloscope, or one’s agility in soldering a piece of wire. It also includes mental skill, which is the ability to think through a problem, or a nagging feeling that something isn’t quite right. It also includes the ability to know what is the best and most accurate way of doing something. For example, why can’t a student simply make one measurement of the restoring force of a spring, make the corresponding measurement of the spring extension, and then plug those values into the Hooke’s law equation to find the spring constant? Why do we have to make a series of measurements instead? The ability to know why we need to do that is an acquired skill in proper technique to test a particular relationship of two different variables. One acquire such skill after consciously and repeatedly learning ways to make such tests. However, the students need to be told that these are the skills they are being taught, so that they are consciously aware of what they are doing and why. So often, in the usual physics labs, this awareness is lacking and not being emphasized.

What the labs can do is reveal in a very direct way how we gain and verify knowledge. What exactly is the relationship between variable x and y, and how do I test it? How do I know my result is valid? In the end, without one having to tell them point blank, they learn the difference between “scientific evidence” versus other forms of evidence, and they get a glimpse of some form of what people like to call “the scientific method”. Considering that most of them will go on to do other things in life beyond just doing physics (or even science), I would think that this ability to have them understand what is involved in determining what is valid is something extremely valuable. This lack of understanding can easily be the cause of why people accept pseudoscience and other flaky ideas. That is why I consider these physics labs as extremely important not just in physics, but as part of a general education of the population.

Since I’ve already mentioned what is wrong with the current way of doing intro physics labs, I should put my money where my mouth is. What exactly should we do in such courses? In the next part, I will give an explicit suggestion on how to revamp these lab sessions.

Part 3

To me, the biggest problem with the current structure of intro physics lab is that we give students a list of things they have to do and measure, and hand-hold them into getting the result. In other words, they don’t have to think too much to complete the exercise. They may have to do a bit of thinking and understanding of physics to complete the write-up, but the actual part of performing the experiment requires simply the ability to follow instructions.

I believe that we should have a more open-ended experiment to be given to the students. So I’ll give an example. Note that while thing is something that I’ve thought about for a while, I’m still writing this off the top of my head. So there may be other problems with it that I haven’t carefully considered.

Give them a problem to solve such as something like this:

Construct a pendulum clock. To make this clock useful, it would be helpful if the pendulum can swing back and forth once as close to 1 second as possible. Then each complete oscillation will take just one second. That way, this clock and measure time in increments of one second. You may use a stop watch to calibrate your pendulum to verify that it makes a one-second swing. Try to build this as accurately as possible. You must describe in detail in your lab report how you accomplish this task and why you chose to do it this way.

Now, as apparatus, give them a length of string, a set of weights, and a stop watch, plus other necessary items for them to be able to mount the pendulum on something.

Here’s what I expect to occur. You’ll have some students doing this by trial-and-error. They’ll mount a length of string, and then start changing the weights to change the period of oscillation. Of course, there’s no guarantee here that there is JUST the right weight for that length of pendulum to produce a 1-second period of oscillation. So students doing it this way may face a problem, but that’s OK, because at the end when we discuss on to do such a thing, they’ll discover why their technique isn’t the best way.

You’ll also get a bunch of student who would use a fixed weight, but tries to vary the pendulum’s length. Again, they may try this simply by trial-and-error, adjusting it a little bit at a time until the period is close to 1-second interval. This technique is of course, more “refined” than the earlier one, since there’s a high possibility of getting the right period.

Of course, what should be done, rather than simply doing a trial and error method, is simply to use a fixed weight, then measure a set of period corresponding to a set of pendulum lengths. Using the table, one can plot period versus lengths, and from there, interpolate (or extrapolate, depending on the range of lengths that were used) the exact length to produce a period of 1 second can be read off. So after the experiment is done and the students write their report, the lab instructor can start a discussion on the best possible technique to get the most accurate result. One can even make it a bit more complicated and ask the students how accurate is their clock as they let it swing for a length of time. This is where if they constructed a clock that swings over a large angle of oscillation, they may discover that it doesn’t keep time very well.

What this type of lab forces them to do is think on the relationship between two measured variables. The first group had to figure out how the period changes as they change the weights. The second group is finding out the relationship between the period and the length of the pendulum. There may be a 3rd group that may be changing both the length and the weights simultaneous. If they do, and they’re doing this by trial-and-error, god help them! :) But no matter what, the students are forced to think of what to do, and why they’re doing it, to accomplish the task. They are not told how to do it. The experiment and the equipment give are familiar enough to them that this isn’t something out of the ordinary. In fact, when they were kids, they probably played with something like this. The curiosity with finding how to do things is the purpose of the lab exercise. It is really playing, it is just that now, they have to think on what they are doing, why they are doing it, and how to present it in writing.

Next time, I’ll try to present another possible laboratory exercise along this line.

Part 3 – Follow-Up

OK, I got some very interesting responses to my suggestion of an experiment that can be done for an intro physics lab. I think I didn’t explain myself too clearly on the premise and how I’m going to present it on here, so I should do that now.

While I tried to be explicit in describing the experiment and what would be a good way to do it, I don’t actually want to reveal the whole hand. That’s why I went along with the idea that there could be a dependence of the period with varying weights, because that is a very likely path that the students might attempt. If someone is thinking of actually trying to introduce this experiment in an intro lab, I don’t want the possibility that some student might google it and find my blog where the whole thing has been revealed. :) That would defeat the purpose of them doing this without any kind of “previous knowledge”.

So while I’m trying to be as clear and complete as possible in the experimental description, and the “philosophy” behind it, I don’t really want to reveal everything either. In fact, I’m hoping that there WILL be students who decided to figure out if they can do it by changing just the weights. I consider discovering something that cannot work to be very educational. In fact, in science, knowing what doesn’t work can be quite important (re: Michaelson-Morley experiment). They at least now know that changing the weights would not work. If they are curious enough, they’ll try to find out WHY it doesn’t work, and this is where the physics can be introduced.

Note that the experiment that I had suggested does NOT require that they have learned anything in intro physics. It is quite independent of the lesson they might have received in class. So in principle, this experiment could be done even during the first week of class. It doesn’t require that they had learned about simple pendulum.

Part 4

Continuing with this series, here’s another experiment that I would propose. This would still be something that can easily be done at the beginning of the semester, which means it doesn’t require that the students would have already learned any physics related to it. BTW, in case people think that all the experiments that I’m going to propose are this “simple”, that is not going to be the case. These “no physics” experiments are aimed only at the beginning of the semester and where we want to introduce to the students that physics is nothing more than a systematic way of deriving what is valid and how to figure out a way to understand the relationship between things. It reinforces the idea that one doesn’t need to abandon all that we already know to understand physics. In fact, we need to bringing in our “common sense” and the sense of “play” to do physics, or at least, these physics experiments. As the semester progresses and, presumably, the students’ understanding gets more sophisticated, the experiments should also evolve the same way.

OK, for this experiments, we will deal with springs and masses, so again, it shouldn’t be something difficult. The task this time is simple:

You will be given a “mystery” object in which you need to determine its mass. You are given a set of springs, and a set of calibrated masses. In addition, you will also have access to a ruler and a stopwatch if you need them. Figure out how you can determine, as accurately as possible, the mass of this mystery object. You must describe explicitly how you go about doing this determination.

Now, of course, in many intro physics class, this type of experiment typically requires that they find the spring constant by looking at the extension versus force or mass applied to the spring. I’m going about this the other way. Forget about the spring constant for now. The key thing here is that the student learns about the relationship between the spring extension as different masses are added to the spring. This to me would be the most obvious technique that most of the students would do. They would find the extension of the spring with different masses. Then, when given mystery mass, they may have to do some interpolation or extrapolation to estimate the mass of that object.

Now, there’s also a possibility that some students may do this differently. They could, instead, let each of the known masses oscillates one at a time and find the relationship between the mass and the period of oscillation. They won’t end up with a straight line, but as in the previous suggested experiment, this is OK. While we tell them they need to do this as accurately as possible, in the end, we really don’t care as long as they explain what they did and how they did it. So even if they had to extrapolate/interpolate by hand, this is perfectly fine.

Now, what we can do further is this. For the students that did the first method (hanging the mass and finding the spring extension), we can ask them this:

Now, often it is difficult to get the spring to be very still – the mass tends to oscillate up and down. So maybe it might also be a good idea to see if we can make use of this property to see if there’s an additional relationship here between the mass on the spring, and the period of oscillation. Can you determine the mass of the mystery object this way? Does it give the same answer? It is always more convincing when two different methods give consistent answers.

For those who did the the second method (oscillating the mass and finding the period), you then say:

Oscillating the spring doesn’t allow you to read off the mass very quickly, which is something you need quite often. So is there another way to determine the mass quicker? How about looking at how much the spring extends as you hang different masses? Can this lead you to a different way to measure the mystery mass? Does this value agrees with the one you got earlier? It is always more convincing when two different methods give consistent answers.

.. and voila, you’ve gotten them to do this in both ways! They also learn that in science, it is always more convincing when you can show a consistent result from two different techniques (although, to be technically accurate, these are not really two different techniques, but this is a good enough demonstration at this level). Now the fun starts if they come up with very different answers. This is where they need to figure out (with the help of an instructor) on what went wrong. To me, figuring out what went wrong is as important and what went right.

After the students have done both, you then can pose an additional question such as this:

What you have now is a graph that you always need to use whenever you want to determine a mass. Is there a way to know the mass of something without having to resort to using such a graph? Can we figure out a way in which, if we know how much the spring extends, we can simply punch that number in and out comes the mass?

I think you know where I’m going with this, don’t you? Considering that the students should have a background in sufficient mathematics, they would have seen a straight line equation. If not, a bit of help and hand-holding is called for, which, at this point, should be alright.

So in essence, we have done the mass-spring experiment, but done in a different manner. Rather than giving out the necessary steps that the students have to do, we instead “coerced” them into doing them by a series of questions and tasks that we want them to accomplish by themselves. Inadvertently, they “discover” Hooke’s Law by themselves.

Part 5

I read this post in PhysicsForums and immediately realized that this is an excellent laboratory experiment and a perfect one to follow what I’ve described in Part 4. This was done as part of a test, but I can see this as being quite suitable for an intro undergraduate lab, especially after they had just done springs and Hooke’s law.

Again, this gives them a task, rather than an explicit set of instructions on what to do. They will need to know about the elastic spring extension and also simple, basic mechanics. So this may not be that suitable to be done at the very beginning of the course, but maybe after a couple of weeks or so to make sure the students have been introduced to simple 1D kinematics. But the fact that this student could have done it, and done it well, indicates that this is certainly doable.

BTW, do most “elastic bands” obey Hooke’s law rather well? I remember testing a typical rubber band one time, and it deviated from linearity rather easily. It would be a cruel thing to do to give the students such elastic bands! :)

Part 6

This may be a bit misleading because it is not strictly a “laboratory exercise”. In fact, I think it might be more suitable to be presented during class. Still, it involves the students doing something, so that fits in with the spirit of a laboratory.

This exercise has 2 parts to it. The first is in class where the students are asked to think about a situation, and write down what they think should occur. Then, they get to go out and test it themselves and observe the situation. They then come back and write down what they observe, and compare it to what they wrote earlier of what they THINK should occur. Finally, they get to explain their observations, especially if what they wrote earlier is different than what actually occurred.

So what is the exercise? Here goes…

You are in a stationary vehicle (a train, bus, or a large vehicle). You have a helium balloon attached at the end of a length of string, so the balloon floats freely (without being confined or rubbing against other objects), while you hold the other end of the string. The vehicle then accelerates forward. What happens to the balloon?

The whole point here is to see the effect of the acceleration in a vehicle (on earth) on an object that is less dense than air. You first give this in a class (or a lab) towards the end of the session, and then ask the students to write down what they think they will observe. They don’t have to give you any reason, just what they expect to happen.

Then, give them some way to get a helium balloon. This shouldn’t be too expensive, should it? Maybe they can get on a train to go downtown, let’s say, with a group of their friends. That would be a great way to observe the balloon. Advice them that maybe it would be a good idea to write down there and then some notes on what they observe, and any relevant circumstances surrounding the observation (i.e. was the train packed? Did the balloon float freely? Were the windows open? Was the air conditioning blasting right at them? etc.) Then when they come back, they need to write down exactly what they observed, and compare that to what they wrote earlier before they did the “experiment”.

I would then suggest that everyone discussion what they have done. Who predicted an observation that is consistent with what they actually observed? Who didn’t see what they thought would happen? Why?

Now, it would be OK to tell the students before they did this that they need to make sure that there are no significant moving air, because that would ruin any effects of the acceleration. But I’m even tempted not to say that. This is because if there are students who did not consider this effect, then there could easily be a discussion on the nature of the ‘experiment’, and why the result that these students get doesn’t quite tell you the effects of the acceleration. The “observation” isn’t valid as far as finding the effect of the acceleration in a vehicle on the balloon, because other external factors have intruded into the observation. If these students acknowledged this extra factor, then they have been observant, and understands the non-validity of their observation. If the students did not realize this, then hopefully, other students will point it out during the discussion.

I’m hoping that during the discussion session is where the students start “argue” about the validity of each other’s observation, such as the possibility that the wind or other factors might affect some other’s observations. I’m also hoping that they might try to come up with some physics on what exactly is the most valid observation for a balloon in an accelerating vehicle that isn’t affected by any other external factors. As the instructors, I would suggest you simply stay out of the way, and see how the students are thinking and reasoning their way through this. You can certainly offer some guidance, but the “thinking process” may take awhile, especially if there are many students who observe things differently from each other. They need to weed out which observation is “faulty” as far as answering the question at hand. Once they figured out the valid observation, then they need to figure out why it happened that way. It is the students that need to make their own self-discovery.

BTW, the valid observation in this case is that the balloon will tilt FORWARD, in the direction of the motion of the vehicle. This is, at first, counter-intuitive, because when a vehicle accelerates, objects tend to get pushed back in the opposite direction of motion. So the first inclination is to expect the balloon to tilt backwards. However, a floating balloon is less dense than the air surrounding it. So when the vehicle accelerates, the air surrounding the balloon gets pushed to the back of the vehicle more than the balloon, and thus displacing the balloon forward.

Strangely enough, it observation shouldn’t be THAT unusual, because there’s an identical situation to this that we are quite familiar with. If we apply Einstein’s equivalence of gravity to acceleration, then technically, we are accelerating “upwards” at 9.8 m/s^2. Now try letting go of a helium balloon. It floats UP, in the direction of our “motion”. It’s the same effect we see in the accelerating vehicle. Yet, I’m sure, for many people, the observation of the balloon tilting forward is non-intuitive. If you are lucky enough to have students who actually argue using this point, then you have one heck of a student! I consider the ability to see the similarities of something “new” with something that they are familiar with as a major accomplishment. It is how we can describe many things that appear to be “different”, yet share almost the same type of description or phenomena. I would suggest that if no students realize this, that you bring it up at the end of the discussion.

Part 7

This time, we do simple optics. Again, as a reminder of the whole point of this series is that the students should be given the ability to simply EXPLORE these things on their own (with minimal guidance), and come up with some sort of relationship between two different parameters, all based on the physics which they may or may not have learned. Each of these experiments do not require that they have encountered the corresponding material in class. So there really is no “theory” to “prove” or to verify here. It is pure “play”.

Part A

In this part, there is a lighted object, which will be the source, placed “far away”. The students are given several convex lenses (with different focal lengths) and some papers as their screens. The object here (no pun intended) is to figure out how to get a focused image of the object onto the screen, without moving any closer to the object itself. The student can certainly vary the location of the screen and, to some extent, the lens itself. Ask them to record the position of the screen with respect to the lens when they find a focused image. Ask them to try it with the different lenses that they were given.

Part B

Now ask them to start moving closer to the lighted object and see where they get a focused image on the screen using one of the lenses of their choosing. This time, they should record both the distance between the lens and the image and the distance between the lens and the object. Ask them to do this several times, each time getting closer to the object.

If they have the time or wish to explore some more, let them try this with a different lens.

Analysis

  1. Now, you tell them that they should put these numbers in a table, or a chart, or a graph, etc… anything where that might be useful for them to figure out if there is any systematic relationship between (i) the distance between the lens and the screen where the focused image is formed, and (ii) the distance between the lens and the object. Ask them if they can think of how these two parameters are related. Note that we don’t expect them to be able to know the thin lens equation, and so, we should not expect them to be able to arrive at such a relationship. But they should be able to notice that as the move closer to the object (thus, the object distance is getting smaller), the focused image will be further away from the lens.
  1. You tell them the focal lengths of the lenses that they used. Ask the students to think on how this number (which is a length) relates to all the data that they had collected. If the student is observant enough, he/she will notice that this number corresponds to the distance of the focused image when the objects is “far away”, i.e. while they did Part 1 of the experiment. If the student notices this, then ask him/her what she would do if he/she is given a lens with an unknown focal length, and needs to make a quick determination, rough of the focal length.
  1. When the students finally got introduced to the thin lens equation, ask them to re-analyze the data, plotting a graph, and using the data to extract the value of the focal length of the lenses. This would be a more accurate determination of the focal length.

Again, these experiments, the way they are designed, do not require any sophisticated knowledge of the accompanying theory. In fact, for this particular experiment, anyone off the street will be able to do it. It simply requires a bit of thinking and common sense to try and figure out the pattern in the observation and the data. The students may not be able to come up with the exact relationship between the parameters, but they need to notice the pattern on what happens to one and you vary the other.

 

 

PhD Physics

Accelerator physics, photocathodes, field-enhancement. tunneling spectroscopy, superconductivity

15 replies
  1. mgb_phys
    mgb_phys says:

    Excellent article.
    There is the Nuffield Physics program (might be a UK only?) which tries to bring the learning from trying things out approach to labs. Very much like your suggestion – here are some weights, here is some string, find out about pendulums.

    There is also a need for a 'tools of experimental physics' class, how to use an oscilloscope, read a vernier and basic experiemntal statistics.

    Drop the experiments that don't work. Particularly 'classic' experiments like Millikan's oil-drop, Cavendish's 'G' and anything else when the write-up consists mostly of explaining why you didn't get the correct result.

  2. ZapperZ
    ZapperZ says:
    mgb_phys

    Excellent article.
    There is the Nuffield Physics program (might be a UK only?) which tries to bring the learning from trying things out approach to labs. Very much like your suggestion – here are some weights, here is some string, find out about pendulums.

    There is also a need for a 'tools of experimental physics' class, how to use an oscilloscope, read a vernier and basic experiemntal statistics.

    I think the experiments that I'm thinking of would also be suitable for the "general students", meaning these aren't meant solely for physics/science/engineering majors. Those students will eventually get more laboratory exercises to refine their skills, but for other students, the intro physics lab (and other intro science labs) are the only place where they actually get to do something like this AND actually figure out how to describe nature quantitatively. This is what is lacking for, say, a humanities major to the point where they do not realize that it requires a lot of "critical thinking" to do science.

    So these are not really "physics experiments", but rather, "Nature experiments".

    Zz.

  3. Bystander
    Bystander says:
    ZapperZ

    I think the experiments that I'm thinking of would also be suitable for the "general students", meaning these aren't meant solely for physics/science/engineering majors.(snip)

    "One size fits all?" You ain't the first to dream that dream. The ugly truth of the matter is that analytical thinking isn't just unfamiliar to the non-majors — it is anathema to them, their fields, and to advisors and faculty teaching in those fields or having backgrounds in those fields.

    "Hooking" their interest is the first big hurdle to at least demonstrating analytical, rigorous approaches to investigation, measurement, and problem solving. It's been twenty years since I abandoned "the dream" in frustration. Something I didn't examine in detail that might appeal to the "free lunch" aspect of humanities majors' training is playing with loaded dice, roulet wheels, slot machines and the like — sorta sucker 'em into examining ways to rig coin tosses, bar bets, and other gambling games, and from there to probability, Gaussian distributions, measurement methods, and then into analytical problem solving.

    Don't hold your breath — the pub-crawling days are long past, but I never had any luck keeping the hustlers' interests when they were financing their drinking habits, augmenting pool table incomes, and other things, and they were far more motivated to learn than are most humanities majors.

  4. physics girl phd
    physics girl phd says:
    Bystander

    "One size fits all?" You ain't the first to dream that dream. The ugly truth of the matter is that analytical thinking isn't just unfamiliar to the non-majors — it is anathema to them, their fields, and to advisors and faculty teaching in those fields or having backgrounds in those fields.

    Wow! Isn't that a negative, elitist view… and I disagree!

    I teach the general education intro-class for non-scientists at our university, and it doesn't even have a lab. As a result, I virtually eliminated lecturing in favor of having students read before class (they are quizzed on reading via an online system) in preparation for team-learning activities done in the lecture hall, including small simple labs with readily available supplies. My feedback from the students has been great, and their performance seems to be better than it used to be (I'm presently taking data on both their attitudes and their learning gains).

    In fact… I'm learning from these experiments too. Because I'm looking for cheap supplies (I buy them out of my pocket, and I reuse what I can term to term), I get creative and try things out I think might work (but sometimes aren't sure about). Sometimes, with simple supplies and untested experiments, the results AREN'T what I or students expected… and they do notice and have good questions. Students who did take physics before are seeing it in a new light, because the activities aren't using Pasco sensors, etc, that can cause labs to be written up into cookbook "recipes." (And students on the pre-med/vet and engineering tracts complain about the labs offered in the department because they are so cookbook… our lab director has tons of Pasco equipment he doesn't want broken, but it isn't in the budget to replace simple things like meter-sticks).

    Also: Faculty in other fields do what their students to gain analytical skills. Where do you get the idea they don't? Analytical skills might very a bit from field to field (becoming less mathematical perhaps in some fields), but many of the basics remain the same.

    I will grant one aspect to your post… one size probably doesn't fit all (it never does in clothing… does it?)… I'd add on more mathematical aspects (better error analysis, etc) for students who are planning to pursue certain fields. But that doesn't mean we should neglect our responsibility to nurture critical thinking and stereotype students who are still growing.

    Sorry ZZ… I don't have control of the lab equipment at our institution… if I was, I'd be there with you and your quest for $$!

  5. ZapperZ
    ZapperZ says:

    I too have taught a physics class for non-science major that was populated mainly by premeds. I can tell that there were MANY that were interested in what they're doing, provided that they are presented in ways that THEY can understand, not in ways that another physicist can understand. So based on anecdotal evidence alone, I do not have that skeptical view on our ability to get SOME of the students to appreciate the critical thinking that one can gain out of a physics class.

    These are the same people that we count on to make science-related decision, either by electing representatives that reflect their views, or in support of funding for various science projects. The fact that we are saddled with the current situation means that the task of teaching them about science and critical analysis haven't been done properly. And I see many efforts to try to remedy this. Richard Muller's Berkeley's course and book "Physics for Future Presidents" is one such clear example, and got quite a bit of publicity leading up to the presidential election.

    Unless we want to be fatalistic about it and just simply throw our hands up in the air, one has to try something, even at a small scale, one person at a time. I definitely try to put my money where my mouth is, since I try to volunteer my services each time there's an involvement in introducing physics, and what I do, to the public, students, etc. To simply give up and not even attempt at doing something is not an option for me.

    Zz.

  6. Moonbear
    Moonbear says:

    On that same topic of teaching to the non-physics majors, one reason that biology departments require their students to take physics courses is that the curriculum lends itself so well to analytical thinking and problem-solving that it's a good course to teach that. These ARE skills that these other majors need, but the undergraduate courses don't often teach them.

    I don't agree that labs should be eliminated simply because the predicted result is not obtained. Rather, students should be taught that the lab report is NOT about making excuses for the lack of predicted results, but in how to apply their results to their hypothesis. When I taught undergraduate biology, we PURPOSELY included a lab in which we knew the results would not fit the predicted. The students were supposed to conclude that their hypothesis was not supported and explain a new, alternative hypothesis based on their actual findings. The learning objective was NOT to teach them to write a formulaic lab report but to learn how to formulate, test and refine an hypothesis…in other words, how to do science.

    That said, Zz, good luck. The biggest problem is that while departments support the ideology of creating new labs, new courses, updating curricula, etc., they provide very little in terms of financial support to do those things.

  7. jday
    jday says:

    I am currently involved in an initiative at my institution in which we are actively striving to achieve the most effective, evidence-based science education possible. So, I thought I'd add an unstructured thought or two (or more) to the discussion here.

    First of all, I'm always excited to learn about this kind of endeavour. Hooray for efforts to improve physics education! Even if we're not pumping out physicists, we want all of our university and college grads to be critical thinkers.

    It is important that one explicitly establishes what students should learn – lay out learning goals for the individual course in operational terms of what students should be able to do if they learned all you would like them to. These goals should really(!) include everything you hope students to learn: concepts, vocabulary, specialized skills, critical thinking skills, etc. Establishing clear goals greatly informs the design of the curriculum, as well as teaching and subsequent evaluation methods. If you are interested in examples of the learning goals we've created for our freshman physics (majors) labs, ZapperZ, I'd be happy to share them with you.

    One should also make an effort to scientifically measure what the students are actually learning. Sharing personal teaching experiences is great, but if you want to convince your colleagues that the revamp is required and/or is working, then you almost certainly require quantitative measures of the improvement in student learning. As I'm sure you know, data trumps anecdotes like rock beats scissors. Creating the right kind of assessment tools, however, is easier said than done – it's an iterative process, assessment validation takes time, etc – but it's worth the effort in the end.

    If you are interested in learning a little more about the sorts of changes being made at another institution, check out the paper titled "Teaching Expert Thinking" here and the references therein. This short little article details one of the things ('invention activities') that has gone into our revamped physics labs.

  8. mgb_phys
    mgb_phys says:

    I think the experiments that I'm thinking of would also be suitable for the "general students", meaning these aren't meant solely for physics/science/engineering majors.

    The Nuffield course covered O'Level (ie 14-16year old) and A'Level (16-18) and didn't require calculus so should be suitable for non-physics majors at college.

  9. ZapperZ
    ZapperZ says:
    jday

    It is important that one explicitly establishes what students should learn – lay out learning goals for the individual course in operational terms of what students should be able to do if they learned all you would like them to. These goals should really(!) include everything you hope students to learn: concepts, vocabulary, specialized skills, critical thinking skills, etc. Establishing clear goals greatly informs the design of the curriculum, as well as teaching and subsequent evaluation methods. If you are interested in examples of the learning goals we've created for our freshman physics (majors) labs, ZapperZ, I'd be happy to share them with you.

    I think in my article, I had tried to convey the goal. Strangely enough, it really isn't about learning a particular aspect of a principle of physics. While there is physics involved, it is more on a "sub-conscious" level. Rather, I want the students to discover the relationship between two variables. In the case of the spring-mass system, let's say, it is between the period of oscillation and the amount of mass. To me, that's the most important goal. How does changing one, affect the other? Can the student quantify the relationship?

    I find this extremely important because in real life, many people attribute one or more thing as the cause of another. People say "oh, such-and-such is bad because it causes this". This is exactly a similar situation as what we do in a lab, because one is relating how one parameter causes a change in another. Everything about our decision-making is based on us knowing the relationships between different things and how they affect one another. The discovery of not only the exact relationship between them, but also that there IS a relationship in the first place, to me, is one of the most important skills that one can have. That is why, if you notice in all the experiments that I've suggested, I've emphasized such a discovery first and foremost. Such ability requires almost no knowledge of physics. Even how to phenomenologically quantify the relationship requires almost no knowledge of physics.

    One should also make an effort to scientifically measure what the students are actually learning. Sharing personal teaching experiences is great, but if you want to convince your colleagues that the revamp is required and/or is working, then you almost certainly require quantitative measures of the improvement in student learning. As I'm sure you know, data trumps anecdotes like rock beats scissors. Creating the right kind of assessment tools, however, is easier said than done – it's an iterative process, assessment validation takes time, etc – but it's worth the effort in the end.

    The measure of what the students have learned is their ability to flat out state how A depends on B, and what would happen if one varies B. A "bonus" measurement would be on how close was the outcome based on what they expected before performing the experiment. It is always a tremendous lesson to realize that the result is different than what one had predicted. To me, this is THE part where we learn, i.e. when we're wrong. The balloon in the train part is all about this. This is how science progresses, and that experiment is an opportunity to show that.

    Zz.

  10. jday
    jday says:
    ZapperZ

    I think in my article, I had tried to convey the goal. Strangely enough, it really isn't about learning a particular aspect of a principle of physics. While there is physics involved, it is more on a "sub-conscious" level. Rather, I want the students to discover the relationship between two variables. In the case of the spring-mass system, let's say, it is between the period of oscillation and the amount of mass. To me, that's the most important goal. How does changing one, affect the other? Can the student quantify the relationship?

    You are right, I believe, in that it isn't about learning a particular aspect of a principle of physics: we want to teach our students to 'think like a physicist" (even if they aren't thinking about physics). The primary goal of first-year labs, in my humble opinion, is that students develop skills and attitudes that will be of value no matter what their later academic path may be. They should learn how to make observations and measurements, how to build models that fit those measurements, and derive meaning from the success or failure of those models. Your article does convey the goal of the labs, and I simply meant to emphasize that I see importance in making these goals explicit to the students (but I'll concede that this might be a matter of personal preference). One might share these goals with the students on day one and then refer back to them throughout the term as they are addressed. As an example closely related to the skills you mention, a learning goal might be: you (the student) will be able to analyze an experimental situation in order to identify the variables that might control the phenomenon being studied.

    ZapperZ

    I find this extremely important because in real life, many people attribute one or more thing as the cause of another. People say "oh, such-and-such is bad because it causes this". This is exactly a similar situation as what we do in a lab, because one is relating how one parameter causes a change in another. Everything about our decision-making is based on us knowing the relationships between different things and how they affect one another. The discovery of not only the exact relationship between them, but also that there IS a relationship in the first place, to me, is one of the most important skills that one can have. That is why, if you notice in all the experiments that I've suggested, I've emphasized such a discovery first and foremost. Such ability requires almost no knowledge of physics. Even how to phenomenologically quantify the relationship requires almost no knowledge of physics.

    I have little doubt that your students will get significantly greater satisfaction out of the labs you outline, compared to the traditional cookbook follow-the-step-by-boring-step labs that low-lighted my undergraduate physics education. If students can discover on their own that such relationships exist (and, hopefully, what those relationships are), then you'll be helping to build better scientists AND better citizens.

    ZapperZ

    The measure of what the students have learned is their ability to flat out state how A depends on B, and what would happen if one varies B. A "bonus" measurement would be on how close was the outcome based on what they expected before performing the experiment. It is always a tremendous lesson to realize that the result is different than what one had predicted. To me, this is THE part where we learn, i.e. when we're wrong. The balloon in the train part is all about this. This is how science progresses, and that experiment is an opportunity to show that.

    Agreed. Prediction and discovering where we were wrong is indeed the part where we learn, and research exists to back this claim. See, e.g.:

    Inventing to Prepare for Future Learning: The Hidden Efficiency of Encouraging Original Student Production in Statistics Instruction.
    Daniel L. Schwartz & Taylor Martin. Cognition and Instruction. 22(2), 129–184, 2004.

    I concur that, for example, the measure of what the students have learned is their ability to flat out state how A depends on B, and what would happen if one varies B. In my experience, however, a sizable fraction of instructors are unconvinced that they should endeavor to change they way they teach based solely on statements of personal anecdotes from others – as I'm certain you know better than most, this kind of thing takes a decent effort. It's one thing to tell a colleague that your efforts are paying off, but it's more to show them quantitatively by how much more your efforts are paying. This is all I meant by my statement of the importance of assessment.

    I look forward to reading about your future success with these labs!

  11. ZapperZ
    ZapperZ says:

    I thank Greg for reopening this old discussion thread, now that it is tied to an Insight article. I wanted to continue with this topic because of a recent paper that I read.

    https://journals.aps.org/prper/pdf/10.1103/PhysRevPhysEducRes.13.010108

    It is an interesting study. In it, the authors studied the effectiveness of a physics lab exercise that emphasizes on lab skills, on reinforcing physics concepts, or both. They then look at the evaluations of the students based on E-CLASS assessment.

    They came up with a rather interesting observation:

    By examining raw E-CLASS scores both overall and by item, we found that students in skills-focused courses showed more expertlike postinstruction responses and morevfavorable shifts than students in either concepts-focused or both-focused courses. This result was further supported by an analysis of covariance, which showed that course focus (skills, concepts, or both) was a significant predictor of students postinstruction E-CLASS performance even after adjusting for the variance associated with preinstruction score, student major, and student gender. Moreover, the ANCOVA demonstrated that the increase in score associated with skills-focused courses was larger for women than for men, and the difference was large enough to eliminate or even reverse the typical gender gap. Overall, our findings support the conclusion that students in courses that focus primarily on developing lab skills demonstrated greater success with respect to fostering expertlike beliefs about the nature and importance of experimental physics as well as their affect and confidence when doing physics experiments.

    You'll notice that in the experiments that I have proposed, the emphasize is on such lab skills. Often, the experiments do not even state what physics concept is being tested or is applicable. I think that without making such an explicit connection to a physics concept, students, especially non-STEM students, might feel less intimidated by a physics class/lab. And yet, they will be learning about a systematic and analytical process on discovering correlations and causation between variables.

    Zz.

  12. ZapperZ
    ZapperZ says:

    There is another interesting paper that will appear in Phys Rev PER. It studies the effectiveness of the traditional intro physics lab in the students understanding of the course material. It found no strong evidence that these traditional labs actually made any difference. The conclusion is quite clear:

    Our results have demonstrated a broken link between intended learning goals and measures of student outcomes. Nine different lab courses, designed to reinforce student understanding of physics content from other areas of the course, have been shown to provide no measurable added value to course performance. This was true across calculus-based and algebra-based courses at three very diverse institutions. We hope these results will encourage instructors and departments to critically evaluate whether their lab courses are achieving their full potential.

    If you read carefully, they are not advocating that we do away with labs completely.

    We also note that “studio” physics courses (where labs, lectures, and recitation are co-mingled in the same space and instructors move fluidly between the three forms of instruction) have demonstrated significant conceptual learning gains compared to traditional instruction [7, 23, 24, 45]. It is impossible to separate the con tributions of the labs in this integrated context, but they may provide greater benefits when used in this way.
    .
    .
    In line with many national calls [8–11], our results should strongly encourage institutions to consider alternative goals and pedagogies for labs, especially those for which labs are demonstrably and uniquely effective. There is much research demonstrating the effectiveness of lab-based pedagogies at developing skills such as evaluating data and models, dealing with uncertainty and variability in data, and designing experiments [46–51].

    One need not completely discard introductory lab activities to begin to make improvement. Research has shown that even small elements of open-endedness in activities can improve student attitudes towards experimental physics [16]. Providing students with time, opportunity, and incentive to revise, troubleshoot, or explore by, for example, spreading a single lab experiment across multiple weeks may enable the desired skills focus [35, 46]. Shifting the emphasis of the lab activities towards the quality of students’ process rather than the product they obtain would be key to facilitating that development [35]. It is unclear, however, whether entirely open-ended project-based courses would achieve the desired goals, especially when scaled for typical introductory course enrollments. Indeed, history has suggested that this is not a sustainable framework [2].

    As I've stated my in original goals, I do not see these intro physics lab as being an instrument to reinforce the physics concepts that the students learn in class. Rather, I see it as a means to get student to think of what they are observing, whether there are any correlations between two different quantities, and if there is, is there a causation connection. The last part requires some sort of an analytical evaluation of what they have seen, and might even involve mathematical description and modeling.

    None of these requires that they know about the physics involved. In fact, none of these have to be on physics. The physics labs become a place where people learn about how we understand the behavior of the world that we observe, and how we know something will work the same way next time, i.e. reproducibility. This paper shows that our belief that intro physics labs provide measurable contribution to content understanding of students is clearly not there. The focus of these labs should be in another direction.

    Zz.

  13. gleem
    gleem says:

    I wish to call to your attention (if you haven't seen it) the effort from the University of Maryland to address issues in physics education which seems to have been an issue for over a century (PhysicsToday| May 2017). They include a discussion of the role of laboratory sessions (Physics by Intuition) and even to the extent of eliminating lectures altogether as such including workshop and studio suite structures. Hope it is of some value for your work.

  14. Mister T
    Mister T says:

    I urge all interested in these issues to read "100 Years of Attempts to Transform Physics Education" by Otero and Meltzer. It's on page 523 of the The Physics Teacher, Volume 54, Number 9, December 2016. As a long-time advocate of the types of reform being discussed in this thread, I found it very interesting to learn that these ideas have been around for more than a century.

    By the way, the RealTime Physics curriculum is an excellent resource for the types of lab activities being discussed here in this thread. I've been using it for about 20 years now and have modified it repeatedly and extensively during those years.

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