# Day 70: Hoop Practical & Circuits

AP Physics: Hoop Practical

We finished up a lab practical on angled projectiles. Each group had a different distance from the launcher and figured out how high above the ground to place a hoop. In both classes, some groups had to shift their hoop to one side or the other, but eventually managed to get the projectile though all the hoops. I also had some goal-less problems to try and shift students away from needing to be able to picture the full solution to be able to progress. The problems mostly got ignored, because it was more exciting to watch the parabola of hoops come together and it took most of the hour to get all the hoops in place.

Physical Science: Series vs. Parallel Circuits

Students used the PhET circuit construction kit again, this time using a lab on series and parallel I modified from Eugenia Etkina’s PUM curriculum. I think students  were getting the big ideas, but its very tough to circulate with a full class in the computer lab, so I feel a little blind. Last year, I was able to do the PhET sims on netbooks in the classroom, so it was easy for me to listen i on student conversations and pull them together at the end of the hour to discuss some big ideas. Next year, I might re-work my calendar to make time for a day in the classroom so my students and I have a chance to make sure they are on track.

# Day 69: Angled Projectile Practical & Ohm’s Law

AP Physics: Angled Projectile Practical

We wrapped up yesterday’s mistakes game, then started a lab practical. Each group got a different distance from the launcher, and needs to determine how high off the ground to place a hoop so that the projectile will travel through it. Tomorrow, we’ll setup the hoops so students can see the results. In both this practical and the problems we’ve been doing, I’ve found some of my strongest students get stuck. They usually know what they’re doing, but don’t see their way to the answer yet. I need to keep reminding my students that they can play with the pieces, even if they don’t know what the full picture will look like yet. I might look for a good goal-less problem to combine with the practical tomorrow to help push them towards thinking about what else they can do, rather than what the answer must be.

Physical Science: Ohm’s Law

I’ve found I really like having students use PhET’s circuit construction kit before we get out the batteries and bulbs, so today we went to the computer lab to find a relationship between current, voltage, and resistance. I left the directions fairly open so that students would be designing their own experiments. Since I don’t talk much about units in this course, the simulations ammeter felt like a black box to a lot of the students. I was really intrigued by one student who measured current by counting how many blue dots passed a selected point in one minute, which connects really nicely to the definition of current as the flow of electric charge.

# Day 68: Mistakes Game & Light the Bulb

AP Physics: Mistakes Game

My students LOVE using the mistakes game to go over problems (a few have even decided to sneak in mistakes when they whiteboard problems in calculus), but it doesn’t lend itself nicely to complicated calculations like projectiles. To get around that, I tried having students whiteboard just the set-up to Friday’s problems for the mistakes game. Students embraced it and we had some good discussions about the physics without getting bogged down in the algebra. Since students did not see full solutions to the problems during class, I posted the answers, along with my complete solution to one of the problems, on Google Classroom.

The artist made sure I saw the person on the bottom floor (where they physics room is) is happy and focused, while the history student on the top floor is angry enough to throw a book

Physical Science: Light the Bulb

Students were given an assortment of materials and tasked with lighting a light bulb. Afterward, we watched a clip from Minds of Our Own of MIT graduates attempting the same task. Students were pretty successful at picking out some of the key ideas about what a circuit is. Tomorrow, we’re using the PhET circuit construction kit, and I’ll probably have them start with the same task in the sim to reinforce that a circuit is a closed path since its not obvious with the light bulb.

# Day 102: Kirchoff’s Rules Revisited & PPM

Physics: Kirchoff’s Rules Revisited

Since the last quiz over Kirchoff’s Rules didn’t go as well as I’d hoped, we took some time to revisit the concepts and try a few more problems. Students left a lot more comfortable. They also really responded to an analogy I got from Kelly O’Shea thinking of current as people flowing through a hallway. It was pretty easy to get them to see that adding a new route in the halls made it easier to get around, which helped them get that adding a parallel branch actually reduces the resistance.

Chemistry: Parts Per Million

Today, students did some calculations using parts per million as a measure of concentration. They were pretty surprised at how small a number you get when you convert ppm into a percent concentration by mass, along with the fact that those low concentrations are really pretty significant in their impacts.

# Day 97: Speed Dating

Physics: Circuits Speed Dating

We did some whiteboard speed dating for compound circuit problems. I put different problems at different tables and, compared to when I’ve done all groups working on the same problem, it seemed like students were more willing to try and make sense of what their peers did. One of my favorite side effects is as students get frustrated trying to follow what a classmate did, they get more careful about showing their own work clearly. By the end of the hour, students seemed much more confident with these problems.

Chemistry: Empirical Formulas Speed Dating

This class also did whiteboard speed dating, but with empirical formulas. In my physics classes, the students who are struggling with a concept try to take advantage of this activity by asking a lot of questions when they’re with someone who has it down and working through at a comfortable pace when they’re with someone else who is struggling, which contributes to the value of the activity. In my chemistry class, I saw something very different. When my students struggling with the topic were with a stronger student, they tended to mostly watch what their partner was writing without much interaction or conversation. When they were with another student struggling with the material, both would seem to shut down and wait for the next rotation. I need to keep working with students on what effective collaboration looks like and how their actions in class day-to-day contribute (or not) to their performance on assessments.

# Day 96: Compound Circuits & Empirical Formulas

Physics: Compound Circuits

Students continued to work on yesterday’s compound circuit problems. A few students yesterday traced different paths through the circuits using colored arrows to provide a visual cue for which currents should add up, and a lot of students today found it helpful to add that representation. I was really pleased when a student insisted that the last problem, with the most complicated circuit, was the easiest in the set.

Chemistry: Empirical Formulas

Students finished up the lab from yesterday, then worked on some written problems finding empirical formulas. I didn’t take the time to discuss the connections between what the lab represented and what they were doing in the problems, and many students struggled to not only transfer ideas from the lab, but to bring back skills like converting mass to moles. I need to make sure I take the time to help students build those connections.

# Day 95: Compound Circuits & Empirical Formulas

Physics: Compound Circuits

Students worked on applying Kirchoff’s Voltage Law and Kirchoff’s Current Law to solve compound circuits. A lot of students made use of my colored pencil’s and of Trevor Register’s KVL diagram to help set up their equations. During the labs last week, I had a lot of groups come up with patterns based on ratios (i.e. every resistor in series has the same ratio of potential difference to resistance), but very few students set up ratios in the problems. I found that a lot of groups needed some prompting to think about how the labs last week relate to today’s problems. Next year, I may try doing some compound circuits in the lab or PhET circuit kit as a bridge to pure paper and pencil problems.

Chemistry: Empirical Formulas

Students found empirical formulas for samples of colored beads, where each color represents a different element. My goal was to give a concrete analogy for what is happening in the lab when they find an empirical formula.

# Day 94: TIPERs & Percent Composition

Physics: TIPERs

I introduced students to Trevor Register’s diagram for Kirchoff’s Voltage Law, then turned them lose on some questions from TIPERs that we used for the mistakes game. A lot of groups made good use of the KVL diagrams both in their groups and during the whole class discussion. We haven’t done the mistakes game much this trimester, but groups did a nice job of using their initial errors as a basis for their mistake.

Using the KVL diagram

Chemistry: Percent Composition

Students did a lab to find what percentage of a stick of gum is sugar. This is one of the first quantitative labs we’ve done, and students struggled with a question about likely sources of error in their measurements, so that will take some conversation on Monday.

# Day 93: Parallel Circuits & Reaction Rates

Physics: Parallel Circuits

Students did the real world version of the parallel circuits lab and put the patterns they’d come up with on whiteboards. After seeing that, in series circuits, the ratio of the resistance to the potential difference across a bulb had some significance, I saw more groups paying attention to the relationship between resistance and the current through a bulb in parallel.

Chemistry: Reaction Rates

Students finished up the reaction rates lab from yesterday, and we discussed the results. Students are getting more comfortable sharing their ideas and finding their own connections to the material, which mean there were more students contributing to the discussion and I heard a greater range of ideas shared.

# Day 92: Parallel Circuit Patterns & Reaction Rates

Physics: Parallel Circuit Patterns

Continuing with Kirchoff’s Laws, students went back to the PhET circuit construction kit to look for patterns in parallel circuits. I have a lot of fun listening to student conversations during this sequence. The patterns that lead to Kirchoff’s Laws are just subtle enough to lead to some great discussion (and emphatic debate), along with lots of moments where students think they’ve got it worked out, only to break their own pattern.

Chemistry: Reaction Rates

Students timed a reaction between copper chloride and hydrogen peroxide, then made various changes to speed up or slow down the reaction. Students were doing a nice job of connecting yesterday’s discussion about energy in chemical reactions  (aided by PhET’s reversible reactions sim) to explain why some of today’s changes impacted the reaction rate.