# First Week (Fa14)

Brain dump of what happened in the first week of this semester.

**Astronomy Lecture**

Started the first day by giving students 10 minutes to brainstorm in groups and come up with a list of topics they would like to discuss this semester. Their lists contained a variety of topics but by far the most common topic was aliens. This is fine by me. Aliens and habitable zones will provide a motivation and theme around which to organize our discussions of planetary characteristics, life cycles of stars, searches for exoplanets, and the scale of the universe (which I told them during the second day of class). After their brainstorming, I talked a little bit about how I want the class to work (discussions, tutorials, building on intuitive ideas). The first day finished with an administration of the Astronomy Diagnostic Test which took 25-30 minutes.

The second class period we defined some terms related to the Celestial Sphere and students worked in groups on the first Astronomy Lecture Tutorial. After the tutorial, we went through some clicker questions to check their understanding and I assigned the second lecture tutorial for homework.

**Astronomy Lab**

We built cardboard sundials for our first lab. I wrote some pre-lab questions asking students sketch the sun’s approximate position and sketch a tree’s shadow at different times during the day, but we didn’t pause to discuss these so it’s hard to say how effective they were at cueing relevant intuitive ideas. Every student made his/her own sundial so there was varying levels of discussion and collaboration between groups. We spent the first 1.5 hours inside working through the activity handout and measuring and cutting the cardboard. The last 20 minutes we went outside so students could practice how to use their sundials. It was **VERY** hot and 20 minutes was almost too long to be outside. I told students they needed to sketch their sundial base showing the gnomon’s shadow and that I had to initial their sketch before they could leave. I think this is a good idea, but many students made very poor sketches showing little to no information and I didn’t do a good job of asking to see everyone’s sundial in action along with the sketch so some students may have copied from a classmate rather than testing their own sundial.

**Physics 2**

At least two-thirds of my Physics 2 class had me for Physics 1 last Spring so I didn’t feel the need to spend a lot of time talking about class format. Instead, I set up 5 different experiments around the room that represent various topics for the semester:

– glow sticks with beakers of hot and cold water

– thermoelectric engine with beakers of hot and cold water

– rare earth magnets and a copper tube

– a Gauss Gun

– battery pack, light bulb and holder, wires, and different types of switches

At the start of class I gave students 25 minutes to experiment with the equipment at their table and to think record their thoughts about the following questions on whiteboards:

– describe what is happening using everyday language

– how might you describe what’s happening in terms of forces?

– how might you describe what’s happening in terms of energy?

– what do you notice that’s interesting?

– what questions do you have?

I was very excited about this idea, but it only went so-so. Students were engaged and generally talkative within their groups, but I had to prod them to get them to record anything on whiteboards and most of their discussions focused on simply describing what’s happening with very little discussion of mechanisms. Unfortunately, I’m realizing that our students don’t get very many opportunities to simply observe a phenomenon and then brainstorm on their own what physics concepts might be relevant for building up a mechanistic explanation. I need to think about how to build these opportunities into class more regularly and what type of scaffolding might be needed. Still, the activity provided an engaging first day and I promised students that we would revisit each experiment throughout the semester as we developed the concepts necessary to explain what was happening. After the initial 25 minutes, I gave students 10 minutes to visit the other experiments and then talked a little bit about class format.

For homework, I gave students an online set of questions about cooking times to answer using their intuition. ‘If your stove takes 4 minutes to raise the temperature of 1 cup of water by 20* C, how long will it take to raise the temperature of 2 cups of water by 20* C?’ etc. I decided to leave the questions as free response rather than multiple choice to try to emphasize that I want them to use intuition and the exact answer isn’t important right now. The next class I summarized their intuitive results and tied each of these back to the equation Q=mcΔT and we used this equation to calculate equilibrium temperatures.

Friday we defined internal discussed some clicker questions aimed at differentiating between temperature and internal energy.

**Physics 3**

I started the first day by talking about how Physics 3 differs from Physics 1 and 2 (more opportunity for student input regarding topics, more activities in which students uncover ideas on their own, less structured lab activities). To try to get students excited about the course, I showed a video of a Chladni plate experiment and the Mythbusters video ‘Fun With Gases’ and said that these were both topics we would be exploring in our first unit. As evidence that students really do impact the course, I told the students that a year ago we did not have a lab on Chladni plates, but that students were interested and made a compelling case that the topic fit with course goals and so now Chladni plates are part of the class. We finished the first day by taking the Mechanical Waves Conceptual Survey.

As homework, I asked students to complete the first section of a tutorial I wrote to help students apply their understanding of sine and cosine to understanding traveling periodic waves. We spent the next class period working through most of the rest of the tutorial.

The first lab period was our usual exploration of various wave phenomena using Slinkies and sound waves. This is the first time I’ve given the Mechanical Waves survey so students were a little behind where previous classes have been when they did this lab. Students had good patience and when they got stuck trying to get a transverse wave pulse to reflect on the same side of the string as the incident pulse I pointed them to the PhET Waves on a String sim and suggested that they find what works in the sim and then try to reproduce the effect using their Slinkies. (Interestingly, students started out using periodic waves rather than wave pulses when doing superposition and wave speed experiments. I guess the idea of wave pulses in previous semesters came from reading the book ahead of lab and wasn’t necessarily intuitive.) I’m not sure why, but when looking at the phenomena of beats (recording pressure vs. time graphs on the computer) students were more explicit this semester in connecting this phenomena to the idea of superposition they saw with the Slinkies.