What students find confusing and interesting

Here are snippets from students’ writing about what is confusing and interesting during the semester. Enjoy!


The most confusing thing about Newtons’ third law is that action and reaction forces occur simultaneously at the same time. How do they happen at the same time?


It is interesting how static friction is greater than kinetic friction. Thus, explaining why it is easier to keep a box moving than it is to start it moving.


I like seeing that the problems build off things we already learned. We have to incorporate kinematics into force problems so it keeps me from forgetting things and also shows me the big picture of why we learned it in the first place.


The topic I found most interesting the acceleration on an inclined plane as its interesting in splitting up the weight into two forces and being able to calculate the acceleration with trigonometry. I like to be able to really see how trigonometry can work in real situations such as calculating acceleration as in Figure 3.23.


The most interesting to me is Newton’s Second Law and I think the reason why is because it makes sense and I understand it!


The interesting part of the reading and the example problems and sections is how all of what we have learned in the reading before is found in almost every problem in order to work it out.I think its interesting how there is always a Free body diagram used in almost all problems and how there is always acceleration and velocity in every problem. Its interesting to see Newtons laws applied to every problem done in class and seen in the examples.


I still find it fascinating how the concepts all come together like a big puzzle. I understand why some higher level math is important to learn before getting involved in the concepts in physics. It is like building a car engine. Without all the pieces the engine may not make the car run, but with all the pieces perfectly aligned the engine will be amazing for the car.


The most interesting thing that I found in the assigned reading was the fact if a cart was going down a ramp and suddenly the incline vanished, the cart would experience free fall. I guess I just never genuinely thought about what would happen if you were to take away that angle.


I find it interesting that when an object is on an incline, we can change the x and y axis to match the incline.


The topic that I found that was most interesting was the use of trigonometry in physics. I find it interesting that all of this stuff go well together and that 3 +4 can equal 5.


Realizing that the combine force of the tension force and the normal needed to equal the weight force. For the group problem in class on Thursday, I initially thought that we could find normal force by using the Pythagorean theorem to find the numerical value for normal force. However, one of the group members explained that since the normal force arrow and the tension force arrow would not form a triangle therefore the Pythagorean theorem could not be used to find normal force. To calculate normal force we had to subtract the tension force from the weight force.


The topic that I found most interesting was one of the topics I found to be most confusing, which was the elevator scenario and its sensations. It is interesting to see why we feel the way we do when riding an elevator, whether that being we feel lighter or heavier during our elevator ride. It is also interesting to see and think about scale measurements on an elevator, and how we can apply our knowledge of forces to justify these happenings.


I think it is very interesting that scales measure apparent weight and not your actual weight. The fact that you can change a reading on a scale or that you are weightless in free fall is very interesting.


The most confusing part of class so far for me is the velocity vs time graphs and the position vs time graph. I have a hard time with graphs in general, so in class I am getting them confused and putting/drawing the wrong things down. Nothing else is confusing to me about the lecture, but I do need more practice with graphs.


The sign of acceleration can be confusing, since it is natural to think that speeding up would mean positive acceleration, and slowing down would mean negative acceleration. Since that is not necessarily the case, I would like to talk about the way direction affects the sign of acceleration, in a way that makes it easily understandable.


I am having a hard time understand acceleration with velocity-versus-time graphs. Also understanding the whole concept behind the slope of the velocity-versus-time graph regarding acceleration. Understanding that acceleration as the slope of the velocity graph forces us to pay careful attention to the sign of acceleration. An object undergoing constant acceleration has a straight line. However, a straight line can be towards the positive or negative direction so it then changes the whole interpretation of the graph in assessing acceleration. Reading velocity-versus-time graphs and applying that information to the concept of acceleration.


I found it very interesting that all of the areas under the velocity vs time graphs can be divided into triangles and rectangles to find the total area underneath. This really simplifies the process and takes a concept that seems scary and breaks it down into simple geometry.


Acceleration in general in interesting to me. It is nature to thing when an object is speeding up with would automatically have positive acceleration and negative acceleration when slowing down. After class I now realize that this is not the case and that direction is actually a very important concept. Knowing rather an object is speeding up or slowing down and which direction it is traveling in will in fact lead you to rather the acceleration is positive or negative.


The topic that I found most interesting was honestly how much information you could get from a velocity vs. time graph. I mean, ultimately, you can find the position, distance, displacement, acceleration–pretty much everything we have talked about so far.


The topic that I had enjoyed the most would be that the velocity is the slope of the position versus time graph and that the acceleration is the slope of the velocity versus time graph. I find that interesting that those three go hand in hand. I also find it interesting that you can find the acceleration, velocity and the displacement just by looking at the velocity versus time graph. There are so many ways to acquire data by just one or two graphs.


The topic that I found to be most interesting was the concept of constant acceleration in the example of the rocket as the rocket has a constant velocity but the acceleration is zero, so the relationship is similar to the position and time graphs to velocity and time graphs. I like looking at similar relationships and this made my understanding of acceleration better.


I found interesting how the acceleration vector has an easy way to remember in which direction it goes. When the velocity is speeding up the vectors of acceleration and velocity are in the same direction and when the velocity vectors are slowing down the acceleration and velocity vectors are going in different directions.

Friction Problem

The problem that gripped students this week was this:

A car traveling at 20 m/s slows to a stop in 50 m. A 70 kg passenger rides with out a seat belt. The coefficients of static and kinetic friction between the seat and the passenger are equal to 0.3 and 0.2, respectively. 

Does the passenger slide in his seat? If so, how does the passenger’s acceleration compare to the car’s acceleration? 

Brian’s theory of teaching

1st order approximation: what you say and do doesn’t really matter and has no effect on student learning. 
2nd order: what you say and do strongly affects how students feel… how they feel about you, where they are, who else they are with, themselves, etc. 

3rd order: how students feel about all that stuff affects what they do, but also how they go about doing those things, and how the things they do at one moment relate to other moments and other things. 

4th: what there is to do depends on what an environment makes possible for doing. And since not all environments are equally good for all kinds of doing, a thoughtfully and carefully arranged environment is needed if you care about what it is students might do and how they might go about doing those things.

5th: every once a while students will be doing certain kinds of somethings and feeling certain kinds of ways, and what you say will matter. It will be consequential to what they do next…

Conclusion: spend most of your time on preparing that environment and on nurturing those feelings so as to create a few moments here and there where what you say matters. Try not to fuck it up. But you probably will, at least some the time, and that’s ok too. Just get back to working on the things that matter. 

Merit Pay as Wage Theft

One of the ways in which I see the coming of merit pay and the process we are engaging in differently than my colleagues is this:

I see merit pay through the lens of wage theft. We are basically being told from the administration and board that, soon, future earnings will be stolen from our non-tenure track colleagues and that this money will soon be up for grabs. To distract us from the scheme, the administration has asked us to come up with our own metrics for how we will redistribute these stolen wages amongst ourselves. This slight of hand works, in part, because we have already fallen into the trap of falling in line to make sure that only tenure track faculty are at the bargaining table. Not surprisingly, in a department of 16 full time employees, the bargaining table includes 9 men and 1 woman, and excludes 4 women and 2 men. 

And not surprisingly, the adminstarion has given us an excuse for why to not include them–they (probably) won’t be eligible for merit pay. Of course, you don’t invite the people you are stealing money from. Of course you don’t make it possible for the people you are stealing from to earn it back. Staff in our department I think make about half the salary as tenure track and about a third the amount of our chair. Instructors are not eligible for promotions. I’d rather not pretend that our merit raises dont come at suppressed earnings for our colleagues. 

I’m of mind to at least consider refusing to play the game as the boards wants us to play it. But it’s tempting for our group to “go along” with these changes as “inevitable”, and to see political dissidence on the matter as “unrealistic”, or as “causing trouble” … it’s also tempting for the group to position views like mine as “causing dischord”. Many don’t like idea of Merit pay and reasonably worry that merit pay will contribute to an unhealthy workplace, and with that worry fresh in mind, it’s tempting to let my controversial position slip into that bucket. “Oh can’t we all just accept this and move along… It would much easier if you could be a team player… your tactics would just make it worse for everyone” and of course, no one is explicitly saying those things, but that’s the power dynamic. It’s just easier to start debating the finer points of merit pay rubrics than it is to face the possibility of our complicity in wage theft. No one wants to hear that. 

Plus, the only reason I can even think of writing this in a public place is because I am tenured. That gives me some power to take politically risky positions, but still my power is pretty limited. 

Edit: here is some my current thinking about how to resist while playing the game.

– write rules for merit based pay, but do so in a way that blunts or prevents them from being implemented unless certain conditions are first met. Those conditions could include clauses like (1) all staff and faculty in department must have had cost of living of raises over the past few years at or above inflation, (2) the median salaries for department employees must be nationally competitive for similar institutions, (3) … clauses could address gender pay gaps, staff pay, adjunct pay, whatever. The idea this that merit pay would be distributed to address such short comings before they could be distributed according to merit.  Everyone in the department should be at the table to help us decide. 

Five Things I’ve slowly Started Doing over Time

A few new teacher practices that have been developing in my repertoire are following:

1. Pausing during “Lecture” to ask students to explain to each other what the heck I just said. 

  • This can be surprisingly effective and engaging. Students also tend to pick up on why lecture is often ineffective and value self and peer dialogue. I also do this with students contributions. What the heck did Jamie just say? (Not whether you agree or disagree)

2. Putting up diagrams from a reading, and asking students to explain what the heck the diagram is trying to say.  (As well as what do you notice? What question does this raise for you?”)

  • I’ve done this a fair amount with waves, but I could use this more broadly. Like the category above, this is really about learning “elaborative interrogation” and “self explanation”, which have a good research base. 

3. Pausing during a clicker question to ask students to not talk about the answer to question (yet), but to explain to each other what this question / situation even is.

  • This proves useful, especially when almost whole class has voted the wrong way. 

4. Putting up two equations that are similar but different and asking students to compare and contrast. 

  • I want to structure this better, but I’ve used this before leading into card sorting tasks where some of cards are equations. 

5. Having post lab questions that require students to read textbook. Like what does this lab have to do with equation 5.3? Or, in section 2.8 there’s a paragraph about such and such. In light of our lab, how are you making sense of this now ?

  • This again is about getting students to engage in productive reading through self explanation, but I’m also helping them to see class resources as connected. 

A lot of these moves are geared toward:

— understanding ideas that are presented to us, whether a teacher, peer, or text. Literacy as broadly construed. 

– observing and trying to understand before evaluating, judging, or answering. 

– learning by actively looking for relationships among disparate parts (diagram and text, lab and text, etc) . Skempian in my kind. 

Vectors and Static Equilibrium (Brain Dump)

Next week we dig more deeply into vectors and tackle more complicated static equilibrium problems.

We start with different stations that are set up to support a 4N weight. For each, students have to draw a FBD and then read off force values from either spring scales or force sensors. The goal is to explain “how the individual forces” work together to support the 4N weight. 

Students are asked to compare and contrast the scenarios and try to come up with a general rule. Some cases are easier to account for than others. There are 4 vertical forces only cases, one with vertical and horizontal, and then a few cases involving angled forces. 

I have to revise the structure of this a bit, so that they encounter complexity unfolding grdaually, while also keeping it brisk (not rushed or lethargic)

After discussion, Students are formerly introduced to concept of vector components, they practice a bit with that. Clicker questions and practice exercises. 

We formerly extend N2nd law to component form. And then we practice some problem solving  with static equilibrium. There’s a particular way I like to model this:

1. Draw actual free body diagram 

2. Redraw free body diagram with components (no trig, just draw and label)

3. Redraw 2 separated 1D FBDs

4. Solve the two simple problems using reasoning we have done previously.

5. Use triangle geometry to piece it back together.

The philosophy here is turning a hard problem into two easier problems you know how too solve. 

Blah blah blah. 

Merit Pay is Coming

We have a new board governing our university, which is much more business oriented. And with that orientation comes merit pay.

Each department (the chair) it seems will get to decide how merit pay is allocated, and our chair rightly wants to involve us in the process. Some are proposing we use rubrics to make things objective, but I am more inclined toward accepting subjectivity with checks and balances that put different constituencies and interests into power.

I am thinking a departmental committee consisting of four (maybe five or six ) members:

Department Chair 

One full professor

One assistant or associate professor 

One full time instructor 

These would form core, but I could imagine asking either the dean (or assistant dean) and/or asking a student representative (e.g., president of SPS) to be on the committee. 

Nominations are made to the committee and maybe some form that outlines rationale in some number of categories:

1. Contributions to (research) profile of department (e.g., grants, publications, prestige) –> this gets at what university cares about. 
2. Contributions to departmental infrastructure (curriculum, programs, etc) –> this gets at what makes our department run 

3. Contributions to students (mentoring, undergraduate research, excellence in teaching) –> this gets at who we serve 

Committee members would vote on each nominee (yes,no, abstain) and the number of votes each nominee receives contributes to a slice of merit pay slice. Those votes could be public or anonymous? Not sure.

Help me think through this? What’s the good and bad? What tweaks could be made? What other options would be better? 

Solving Forces Problems (Brain Dump)

Next few weeks in first semester physics we start  solving forces problem.

I’m doing this in a couple stages:

  • 1D Horizontal dynamics: 
  • 1D Vertical dynamics and weight 
  • Friction
  • Static Equilibrium in 2D
  • Dynamics in 2D
  • Interacting Objects

Here are some details about what we are doing this week. 

The horizontal dynamics starts by building off our half Atwood’s experiments, by introducing a second pulley that pulls back on the cart. 

This introduces us to the idea of net force and representing forces using FBDs. We do some card sort ranking tasks (rank Fnet and rank by acceleration) and clicker questions with FBDs. 

Students end up solving three problem types: unknown acceleration, unknown mass, unknown force. I’m doing so, We also cycle back to review kinematics, since our forces Problems with unknown acceleration involve finding a final speed and position. Students are expected to make graphs and equations that represent motion. 
The vertical dynamics begins with gravitational force lab, to introduce model  concerning 10 N/kg. Using demos and clicker questions, we talk about how to properly and improperly use scales (if you want measure your true weight), and build up idea of apparent weight as normal force. We do some card sorting activity of situations where normal force would be larger than, less than, equal to, or not enough information to decide.

The day ends representing and then solving elevator ride problems. We actually get on elevator with vernier scale, and use that data to determine mass or rider, top speed, and total distance traveled. 

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