## Day 29: Practice Constructing Explanations through Computational Models

Inspired by last Friday’s professional development where we focused on students making observations, asking questions, and constructing explanations for phenomena; I wanted to provide my AP Physics 2 students with some practice in this area. We started with a computational model of two gases in the same container. One gas initially has a higher temperature than the other and is positioned on one side of the container. As the model runs, students can observe the interactions among the atoms of the two gases and the resulting histogram of rms velocity. Students made observations in groups, defined additional questions to investigate, and changed the parameters of the model accordingly. After plenty of time to investigate and discuss as a group, students individually wrote their own explanation of the phenomenon in the span of five minutes. Each group than read their explanations to each other, provided feedback, made revisions, and selected one explanation to share with the entire class. Each group than shared their selected explanation with the entire class and the entire class, including me, provided feedback. If students didn’t comment on their own, I took the opportunity to highlight explanations that cited our existing models as evidence, explained the phenomenon from both a macroscopic and atomic perspectives, and correctly used the vocabulary we have been practicing in our study of thermodynamics.

After this discussion, student then looked at a modified computational model where the two gases are separated by a barrier that prevents each gas from crossing to the other side of the container but allows collisions between atoms across the barrier. We didn’t have time to go through the entire observations, additional investigations, and explanations cycle again, but students did connect this model to heat transfer via conduction.

##thermo ##computationalmodeling

## Day 28: Heat Transfer Lab Discussion

Today AP Physics 2 students discussed their observations and explanations from the heat transfer lab. Different groups did different parts; so, it was important to spend some time sharing. I missed the lab, but I was able to wander around and see the data and graphs that were exported from Vernier’s Graphical Analysis app that ran on the Chromebook and viewed data from the LabQuest 2 interfaces. This was their first time interfacing the LabQuest 2 with their Chromebooks and it went well even without me there! Here is a a graph from a group observing the effects of heat transfer by radiation on two cans (one painted black, one silver) of water.

##thermo ##equipment ##tech ##labquest2 ##chromebook

## Day 27: Heat Transfer Lab

Today, AP Physics 2 students explored all three types of heat transfer. With unpainted and black-painted cans of hot or room-temperature water, heat lamps, and fans; students explored heat transfer via conduction, convection, and radiation. This is one of my favorite labs, and I was gone to work on the alignment of our science curriculum with the Next-Generation Science Standards. I left them with an awesome sub and a cart full of goodies.

## Day 26: LabQuest 2 and Chromebooks

I’m going to be out of the classroom tomorrow to work on the alignment of our science curriculum with the Next-Generation Science Standards. So, today, I demonstrated to students how to connect to the LabQuest 2 from their Chromebooks, export the graph, and export the data. I expected that we would have done this already this year, but so far we only had to manually record data from the LabQuest 2. In tomorrow’s lab, they won’t want to manually copy 60+ data points. I used my new HDMI-to-VGA connector to display the Chromebook screen and the Elmo to display the LabQuest2 screen.

##thermo ##tech ##labquest2 ##chromebook

## Day 25: Whiteboard Discussions

Today in AP Physics 2, we whiteboarded (okay to making that a verb?) three problems. Two groups whiteboarded each problem and we compared and contrasted the two solutions. For one problem where students were calculating the increase in pressure in a tire due to an increase in temperature, both groups presented similar solutions and the same final answer. Fortunately, one student spoke up and questioned the final answer of both groups. He pointed out that both groups failed to based their calculations on the absolute pressure in the tire and instead used the gauge pressure. It was great to watch him explain the error and his solution to the entire class as he spun around in his chair so he could address everyone. I captured a couple of pictures mid-spin, but he noticed me!

##thermo ##whitedboarding

## Day 24: Kinetic Theory Activities

I inherited these kinetic theory activities from the physics teacher who retired when I started. I’ve always used them as they require students to look at everyday occurrences from a very different perspective (through the lens of kinetic theory). I think these activities are even more important this year with AP Physics 2 as I infer that the new course emphasizes students mapping reasoning between macroscopic and atomic scales (“connect and relate knowledge across various scales…). As a result, I really emphasized the translation between macroscopic observations, measurements, and properties; and the corresponding atomic properties. Students surprisingly struggled with this shift of scale. For example, students struggled to reconcile that from a macroscopic perspective, a bouncing rubber ballâ€™s kinetic energy is decreases and is transferred to thermal energy and from an atomic perspective the kinetic energy of the atoms in the ball increases. Initially the student started his explanation by stating that the kinetic energy of the atoms in the ball decrease. I occasionally directed the discussion back to considering the computational model of an ideal gas that we have been exploring which appeared to help students span the macroscopic and atomic worlds.

One of the activities is to cup your hands around an inverted flask and observe what occurs (bubbles leave the lower beaker):

[Update: 30sep2014] Here is the activity handout.

##thermo ##labs

Today in AP Physics 2, we continued to explore the computational model for the atomic model of an ideal gas by varying the properties of the model (e.g., make the atoms heavier, increase the temperature, decrease the temperature). I also introduced the First Law of Thermodynamics by reviewing the Energy Transfer Model (ETM) from last year.

Outside of class, I started to score some labs. I had students write their labs in Google Docs and submit them to Canvas via the Google Drive integration. As a result, this is what I see in SpeedGrader:

Perfect!

## Day 22: Computational Model for Atomic Model of an Ideal Gas

Yesterday, I presented the atomic model of an ideal gas, which students are familiar with from chemistry, from a physics perspective. I didn’t have a paradigm lab to introduce this model. Instead, I shared a GlowScript computational model ported from the VPython hard-sphere model of a gas. We didn’t have time to explore the model today, but will on Monday.

This evening, I read about a much better way to start this unit from Scott Thomas. He had his students develop and explore this computation model over an extended period of times and find the relationship between average kinetic energy and temperature. Next year will be better!

## Day 21: Breaking the Fluid Dynamics Model

Today in AP Physics 2, we tied up some loose ends related to fluids before starting thermodynamics. When students performed the lab practicum a couple of days ago, almost all of them placed the cup too far away despite accurate measurements and an accurate computational model. I took this opportunity for us as a class to discuss what sources of error may have been present. When discussing a loss of energy as the stream exits the bottle, I shared a journal article from The Physics Teacher: “Determining the Coefficient of Discharge for a Draining Container.” This article was a great way to finish the fluids unit in that it was accessible to the students and demonstrated the limitations of our fluid dynamics model.

##fluids ##practicumlab

## Day 20: Standards-Based Grading for AP Physics 2

Today, AP Physics 2 students had their first major exam. This is the first time students were directly exposed to the different standards-based grading methodology that I’m trying with AP Physics 2. When the look at the grade book, they will see something like this:

Over time, all of the AP Physics Big Ideas and Enduring Understandings will be represented. To maintain the focus on complex problems that integrate multiple concepts, students taking reassessments will take another entire exam that covers all relevant enduring understandings.

If nothing else, I think reporting learning in this manner will reinforce the big ideas that connect the varied topics that comprise AP Physics 2.

##sbar