Bringing focus back to intro lab work
While I was out on paternity leave, I had the occasion to come back to school for various meetings and to help set up for labs, and during one of these visits, I was able to observe my introductory physics students squander the greater part of a full lab period. It was interesting for me to see, as I wasn’t officially the “teacher”, and so I decided to send them the following feedback from my observations.
I was rather disappointed with the level of engagement I saw in the
lab today. I saw many instances of entire groups doing very little
work, or people sitting around while one person tried to do the entire
experiment on their own. I saw very little questioning among group
members—how will we measure acceleration, or how will we measure
force? And I saw even less being written down. This is very
disappointing, and far below what I know you to be capable of.
There are sure to be excuses. I was not there to ask you questions,
PDC mania is sweeping the school, whatever. They are excuses, nothing
more. In these moments, when no one seems to be watching, and the
temptation is to be distracted and do no work, you are falling far
short of what you could be learning. Being confused is natural—the key
is how you deal with that confusion, since it is most often the first
sign that you are learning something worth learning.
For homework, I would like for you to write me and Mr. M an email. In
this email, please answer the following things:
1. What did YOU personally do in lab (what data did you take, what
things did you write down, how were you involved in the experiment)? I
fully expect many of you to write to us with the answer or nothing, or
next to nothing. It takes courage to admit this.
2. What did your group learn in lab—what did you observe about the
velocity, or what did you learn about how to measure acceleration or
force). Again, it’s quite possible that your answer here could be
You will be getting more time on Monday to work on this lab. It turns
out that the discoveries you will make in this lab are among the most
important discoveries in physics. They allow us to predict the path of
everything from baseballs to lunar landers.
3. Explain to me and Mr. M how you will engage lab on Monday
differently. I’m looking for a substantial and thoughtful answer here.
What questions do you have about what you did? Where did you get
stuck? How are you going to overcome this and make a major
This email got some wonderful responses. I’ll share one below:
Hey Mr. B and Mr. M,
1. In the lab on Thursday, I helped take a video of the spring using Video Physics. We did not realize that we should have been using the motion detector and connected it to a computer and used that graph, but we were able to get a graph on an iPhone that seemed to work. I helped draw the graph that the phone produced on the whiteboard. I did not take any notes on the lab, or write anything down and I probably should have. After I had written the graph on the whiteboard, we still had plenty of time to experiment and maybe figure something else out but we didn’t, and we just played around and didn’t accomplish anything else.
2. After we had a graph on the iPhone, and I had drawn it on the whiteboard, we didn’t do anything else. We didn’t really talk about the importance of the graph, or try to find any equations so we didn’t really learn very much. We did see that the graph had a constant velocity, but we didn’t go any further than that, even though we had plenty of time to. We got distracted, and we just played around with the springs and didn’t bother to get into any details about the graph.
3. Tomorrow, when we work on this lab, I am going to change a lot of things. For starters, I am going to stay with my group. To be honest, I switched groups on Thursday, and I worked with P, J, and T which was a bad idea. I am good friends with J so we got distracted and we didn’t get much work done. I have learned from this mistake, and it will not happen again. I am going to stay with my group on Monday, leave my phone in my backpack, and bring paper and a pencil to take notes. I am going to stay engaged in the lab, and remind my group members that we need to stay focused and work on the physics problem at hand. I am going to be asking lots of questions and hopefully get a lot accomplished and learn something new.
I am sorry that I was not focused on Thursday, and I wasted time in class that could have been used to make observations and learn more about acceleration and velocity. I promise that I will be more engaged on Monday and stay on task.
As you can see, my students are pretty honest and wonderful, and if anything, I worry that they are occasionally too compliant.
Here’s what that same student wrote back on Monday after lab:
1. Today I helped my group record data and observe the actions of the
cart when the fan was turned on. We first measured the distance and the
time, and we were able to get a velocity vs. time graph. We then changed
various variables, such as the force, which was generated from the
batteries, and the mass, which was varied based on the amount of
batteries we added to the top of the cart. We took all of this data,
plotted the points, and made graphs.
2. The big idea we discovered today was the relationship between the
acceleration and the force, and the relationship between the
acceleration and the mass. Our data didn’t give us an accurate graph,
and didn’t really make sense…but after we discussed it today with the
class we found that the acceleration and the force form a graph that
looks very similar to the graph that was produced from the pendulums at
the beginning of the year. This was a great discovery and we then
realized how much we could do with this data, knowing that we can find a
constant, linearize the graph, and discover more about this relationship
which we are looking forward too. As well, with the acceleration and the
mass, our data was not accurate (which my group is really frustrated
with, but we hope that we will be able to figure this problem out and
fix it when we have more time in class) but when discussed with the
group, we came to the conclusion that the mass does affect the
acceleration, but it is proportional. It has a constant slope on it’s
graph, and when the mass is increased, the acceleration decreases and
vise versa, which makes sense when you apply it to everyday activities.
The heavier an object is, the slower it travels.
3. My participation was extremely different. I did everything that I
said I would do, I left my phone in my backpack, I brought a piece of
paper and pen to take notes, and I stayed with my group. We got a lot
done, and accomplished a lot and we were building off of each others
questions and making predictions and all engaged in the experiment. We
were all working together, one person timing, one recording, one letting
the cart go, one catching it. After the class we felt good that we had
learned something and accomplished something, and we were looking
forward to today’s class to share our findings with the class.
4. I want to know why our data wasn’t accurate. It was frustrating to
realize that we spent two class periods conducting an experiment that
yielded incorrect data, but maybe we had a misunderstanding in how we
were executing the lab. I am trying to stay relaxed and realize that
this is a mistake that I can learn from and grow from, but I am anxious
to know what went wrong and how to fix it!
I think I’ll call that progress.