# Day 103: Mystery Circuits, Explosions, & Formula Relay

AP Physics: Mystery Circuits

Students did a lab practical from The Physics Teacher to figure out how three light bulbs were wired together without opening the boxes. I did a little extra front-loading by asking students to sketch circuit paths and KVL diagrams, which set them up nicely to figure out what was going on in their box. A lot of students are disappointed that this is effectively the end of our circuit unit; its too bad I can’t direct my students towards the electronics courses in the IT department since they are seniors.

Physics: Cart Explosions

Students started collecting data on a series of cart explosions to introduce conservation of momentum by plotting the ratio of the cart masses vs. the ratio of the distance each traveled in order to hit the end stops simultaneously. I didn’t overhear any groups anticipating where to start their carts, which is unusual for this lab, but some groups were able to make limited predictions with a little prompting.

Chemistry Essentials: Formula Relay

Students did some more formula writing practice. Today, I had them work on whiteboards and required them to rotate who did the writing. A lot of my groups have fallen into a pattern where one or two people do most of the intellectual heavy lifting, and it was clearly challenging for them to have to articulate what to do instead taking the marker. There were also some students who have been relatively passive during group activities who seemed like they started to get the hang of formula writing, which is exactly what I hoped.

# Day 102: Whiteboarding

AP Physics: Circuits Whiteboarding

Students whiteboarded yesterday’s problems on circuits. Students are recognizing the value of sketching circuit paths and KVL diagrams more quickly than some of the other diagrams this year. My students say its because the value of the diagrams is very obvious, but I think its a factor that they’ve come around to the value of other diagrams in the class.

Physics: Impulse Whiteboarding

Students whiteboarded yesterday’s problems. A lot of students referred back to last week’s paradigm lab on impulse and Friday’s qualitative problems, which was fantastic. I also had some students who couldn’t remember doing either the lab or problems and struggled quite a bit today as a result; I need to keep working on helping these students see the value in being an active participant in their lab group.

Chemistry Essentials: Formula Writing Whiteboarding

Students whiteboarded yesterday’s problems naming formulas with polyatomic ions. Each day, things are clicking for a few more students. One of the big keys is understanding the relationship between the charge and the electron diagram. At this point, I’m leaving it up to students whether to sketch the electron diagram, but many are choosing to sketch it because they find it helpful.

# Day 101: Circuits, Quantitative Impulse, & Polyatomic Formulas

I had a sub today, so no photos.

AP Physics: Circuits

Students started working problems using Kirchoff’s Laws. Since our post-lab discussion was cut pretty short, I put a suggestion on Google Classroom to try building some of the problems in PhET’s circuit construction kit; I’ll be curious to hear whether any students tried that.

Physics: Quantitative Impulse

Students started solving problems using the equations for momentum and impulse.

Chemistry Essentials: Polyatomic Formulas

Students translated between names and formulas for compounds that include polyatomic ions. That is usually a tricky shift in this course, so I’ll be making sure we go over the worksheet carefully on Wednesday.

# Day 100: KVL Diagrams, TIPERs, & Formula Writing

Today classes were shortened due to a pep fest.

AP Physics: KVL Diagrams

We had a very brief discussion about the results of the labs from Wednesday and Thursday; students were consistently very successful at picking up on they key patterns I wanted them to see. I also introduced them to Trevor Register’s KVL diagrams. I like to pair that with color-coded current paths on the circuit diagram.

Physics: TIPERs

Students worked through some conceptual problems on impulse and momentum, mostly taken from TIPERs to get them thinking about what the equations we have so far really mean. A lot of groups really wanted to start by guessing an answer, then come up with some physics to justify it, rather than the other way around. I’ve been encouraging students to use CER with these types of problem, starting with the evidence and working towards the claim, but I’m tempted to try and talk my department into switching to ERC to make the evidence first more explicit.

Chemistry Essentials: Formula Writing

Playing the mistakes game yesterday seemed to help some students start to make sense of writing chemical formulas, though a lot of students still need more practice. Today, I gave students some formulas and asked them to determine whether they are possible based on what we know about bonding. This seemed to help the concepts click for a few more students.

# Day 99: Kirchoff’s Laws, Impulse, & Mistakes Game

AP Physics: Kirchoff’s Laws

Students used PhET’s circuit construction kit to look for patterns in the current and potential difference in both series and parallel circuits. I usually do the PhET version before the real-world version we started yesterday, but testing season makes it tricky to reserve a computer lab right now. I overheard some students making good connections to their work yesterday and noticing the key things I wanted them to notice.

Physics: Impulse

Students re-did the impulse lab from earlier this week. This time, I spent more time discussing with them why we care about the change in velocity, rather than the velocity at a specific moment. Students were more visibly attentive when I walked through how to get the change in velocity on a LabQuest than they were earlier in the week; I think it helped that they knew we were re-doing the lab because their earlier results came out poorly. I also had groups assign someone to plot their data as it was collected, which had them thinking about whether their results make sense throughout the lab. One section got beautiful results, while the other still had slopes all over the place; I’m not quite sure what happened in the second section.

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Chemistry Essentials: Mistakes Game

Students whiteboarded yesterday’s problems using the Mistakes Game. The students who are using the electron diagrams as a thinking tool are pretty quickly getting the hang of things.

# Day 98: Kirchoff’s Laws, Board Meeting, & Chemical Formulas

AP Physics: Kirchoff’s Laws

Students started working on a lab for Kirchoff’s Laws. They measured the current and voltage at different points in the circuit to start looking for patterns. I overheard some good discussion about how the results connect to the Ohm’s Law equation we got earlier this week.

Physics: Board Meeting

Students whiteboarded their results for the impulse lab, but the slopes of their graphs were way off from what I expected. A lot of groups admitted that once they got their hands on the equipment, they ignored that we were interested in the change in velocity, rather than just the maximum or the minimum. I need to think about how to adjust pre-lab discussions in this course to keep students focused on the key ideas. We were able to get some qualitative ideas about impulse in place from the results, but I decided to have students collect data again tomorrow to get a quantitative understanding.

Chemistry Essentials: Chemical Formulas

Students started writing chemical formulas given the name of the compound and the charges. I got out some beans for students to use as manipulative versions of Lewis dot structures, which helped a lot of students get beyond “flop and drop” when figuring out subscripts. Some students did get thrown by switching between electron diagrams and particle diagrams, so I need to work on keeping the types and purposes of diagrams distinct.

# Day 97: Board Meeting, Impulse, & Valence Electrons

AP Physics: Board Meeting

Today, we had two board meetings. First, we discussed the results of last week’s electric potential difference lab, followed by yesterday’s work on Ohm’s Law. The potential difference discussion went well, but the Ohm’s Law lab was trickier. This is the first lab I did as pretty open inquiry where students were working with three different variables, and a lot of groups struggled to relate all three. Next year, I may go back to having students do two separate experiments. There were also several groups who used the battery’s internal resistance and I think a little more pre-lab discussion could have avoided that.

Physics: Impulse

Students tied a cart to a force sensor with an elastic string and collected data for a relationship between the area of the force vs. time graph and the cart’s change in velocity. A lot of students had some trouble with the idea that they were graphing features of the LabQuest graphs, but were able to make sense of what was going on with some support.

Chemistry Essentials: Valence Electrons

Students sketch Bohr models for selected elements to start identifying patterns in the number of valence electrons. Students seemed pretty successful at making sense of why certain elements have certain charges. I also got out the electrolysis machine to give an example of how we know the ratio of elements in a compound.

# Day 96: Circuit Basics, Cart Catching, & Chemical Changes

AP Physics: Circuit Basics

Students used the PhET circuit construction kit to start exploring basic circuit properties and develop Ohm’s Law. It was a lot of fun to listen to students as they discovered new features in the simulation and discussed details they noticed.

Physics: Cart Catching

To introduce momentum, we borrowed the idea of “chalk-smashing ability” used to introduce energy in the PUM curriculum and had students play with how they could make it harder to catch a cart on a dynamics track. I got excited when a couple of groups took advantage of the plunger carts to see how catching the plunger end felt different than catching the other end, which will be a great lead-in to impulse.

Chemistry Essentials: Chemical Changes

Students did several different chemical reactions to identify signs of chemical changes. There were lots of good observations during the lab.

# Day 95: Electric Potential Difference, Conservation of Energy, & Quiz

AP Physics: Electric Potential Difference

Students did a variation on the lab to map an electric field in a tray of water. Since I just wanted to define electric potential difference, they measured the voltage along a line with the multimeter’s ground probe in a few different positions (my article about this lab was in the January issue of The Physics Teacher). There was a lot of good discussion within lab groups about what negative voltages mean.

Physics: Conservation of Energy

Before their quiz, students whiteboarded a couple of conservation of energy problems (which I spaced out on taking a picture of). For a lot of students, this reinforced the importance of the meaning-making steps and gave them a boost of confidence before starting the quiz. The downside is there are students who approach the pre-quiz problems as a chance to cram, rather than a warm-up. I’m trying to decide if I’m okay with that trade-off.

Chemistry Essentials: Quiz

Students took their quiz on atomic models and classifying matter. I’ve been working a lot on the class culture and finding ways to connect with students I’ve been clashing with, and it paid off today when, for the first time, I didn’t have to police students staying quiet after they finished their quiz.

# Day 124: Mystery Boxes & Metamorphic Rocks

AP Physics: Mystery Boxes

Today, students worked through an activity I got from The Physics Teacher. Groups were given a black box with three light bulbs and had to figure out how the bulbs were wired without opening the boxes. I front-loaded some thinking by having students sketch the four possible circuits and do some KVL diagrams and arrows to show currents, which students were then very successful at applying to interpret the behavior of their boxes. The main issue I ran into is many students students initially wanted to treat equivalent circuits with slightly different arrangements as different circuits. For example, groups often drew one parallel circuit with one bulb on the first branch and two on the second, then a second parallel circuit with two bulbs on the first branch and one on the second. The KVL diagrams provided a nice tool for showing why those circuits are equivalent.

Thanks, Lotze, for drilling holes in all the boxes!

Earth Science: Metamorphic Rocks

Students identified metamorphic rocks today. Similar to the igneous rock lab earlier this week, I started by having students sort the rocks based on visible properties. Most groups went with whether the rocks were layered, which lead nicely into foliation. A few groups when with sheen, which is the other major property used to identify rocks on this key. Students struggled to tell the difference between marble and quartzite using the key. After the lab, I talked a little about hardness and the acid test, but it would be nice to give students some tools they can use during the lab to differentiate those two.