One of the Things That I'm Keeping From My Remote Classes

I mentioned earlier that when we went remote due to the pandemic, I forced myself to be trained as an online instructor and received credentials from the school to teach online courses. While I do not intend to be an online instructor, many of the lessons and technique that I learned from such training are actually quite useful even when I eventually went back to in-person classes.

One of the aspect of online classes that I'm keeping even for my in-person classes is the discussion forum. At first, it seems that discussion forum might be a bit of a waste of time, considering that we all meet each other during classes, and can easily engage in conservation and discussion. It turns out that online discussion forum has been quite useful for me. Here's how I implement it in my in-person classes.

I always start the semester with the first discussion topic in Week 1, which is for the students to introduce themselves. I ask them to write a brief description of who they are, what their majors or intended majors are, and what career to they aspire to. I ask them about their hobbies, and anything else that may be interesting and unique about them.

What this gives me immediately is the information on what they are interested in, especially with their ares of study. I like this because I can invoke examples in my lessons that apply to what they want to do. This is something I do frequently, which is a conscious attempt at making the physics lessons relevant to their area of study. Even if it is not applicable to their major, I can also connect this to something they are into, especially if they are musicians and play a particular instruments, when we talk about sound waves, resonance, pitch, etc. Last semester, one of my students was a college tennis player, and we had a long discussion on air flow, Bernoulli principle, etc. when we were discussing fluid dynamics.

But you may ask "Yeah, ZapperZ, this is all interesting and useful, but why do you have to do this over an online discussion forum? Why can't you just ask them in person?".

The answer is, not every student is comfortable with speaking in front of a group of people. In fact, many students are terrified of being the center of attention during class. I am offering a form of engagements in which many of the introverts will be more comfortable with and are able to be more open in sharing who they are. The more extrovert ones are more than welcome to introduce themselves during class time. In the spirit of Universal Design in Learning (UDL), I am trying to provide more than just one means of engagement for the students.

This is not the only topic that I use in the online discussion forum. I'll make another post on another topic that make use of the discussion forum to get a snapshot on how the students think and analyze a particular scenario.

Zz.

Which Comes First, Energy Or Momentum?

First of all, Happy New Year! It's my first post of 2023. I'm crossing my fingers that I won't be as stressed out as I was toward the end of 2022.

As I prepare for another semester of teaching General Physics, I'm struck at trying to understand the logic in the sequence of the introduction of the topics on energy and momentum. I know that as instructors, we have the freedom to arrange the sequence that we introduce the topics that we teach, so this is not a criticism. Rather, it is just trying to understand if there is a rational reason for introducing one ahead of the other.

I'm talking in particular about the topics of momentum and energy. This is because different textbooks introduce them in different order. I'll list a few examples.

• Serway-Jewett: "Physics for Scientists and Engineers" 10th ed. - Energy Chap. 7&8; Momentum Chap. 9.
• Knight: "Physics for Scientists and Engineers" 4/e - Energy Chap 9&10; Momentum Chap. 11.
• Knight-Jones-Field: "College Physics" 4e - Momentum Chap. 9; Energy Chap. 10.
• Giancoli: "Physics - Principles with Applications" 7th ed - Energy Chap. 6; Momentum Chap. 7.
• Hewitt: "Conceptual Physics" 13th ed - Momentum Chap. 6; Energy Chap. 7.

As you can see, different authors/textbooks introduce momentum and energy in different order. My question is, WHY?

From my view, it is more logical to introduce the concept of energy FIRST, and then introduce momentum. This is because a large part of momentum, and real-world cases of collisions, involves inelastic events in which kinetic energy is not conserved. So how does one ignore inelastic collisions when dealing with conservation of momentum? Or, if one does include inelastic collisions, how does one tip-toe around it when the concept of energy (kinetic energy) has not been introduced yet? 

Has anyone done this using the sequence of momentum first and then energy? How did you go about doing it? Is there a rational reason for introducing the topic this way?

Zz.