Chemistry Essentials

Day 84: Electric Potential & Whiteboarding

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Physics: Electric Potential vs. Gravitational Potential

Students worked on a worksheet from the Modeling Instruction curriculum that draws analogies between gravitational potential and electric potential. Several students commented that relating electric potential to something more tangible helped them make sense of what we’ve been doing. I also had a very good conversation with a student about how last trimester, she really liked how connected the mechanics topics were, but doesn’t have the same sense with electricity. This confirms that I need to keep working on my storyline for this trimester, but it was great to hear some of the metacognition the student was doing and I consider it a sign of a good class climate that a student was willing to have that conversation.

Chemistry: More Whiteboarding

Students used whiteboards to work through another stoichiometry problem. A lot of students left with much more confidence than they’d started the day with.

Day 83: Electric Potential Difference & Whiteboarding

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Physics: Electric Potential Difference

In the past, I’ve motivated the need for electric potential difference in addition to electric potential purely through analogies to gravitational potential energy. Today, I tried an extension of the Modeling Instruction lab to map electric potential. I had students measure the voltage along a line in their tray of water with the multimeter’s ground attached to the negative lead of the power supply, then repeat with the ground attached to the power supply’s positive lead and the ground held somewhere in the middle. In the discussion, students agreed that the change in voltage is more meaningful than the specific value.

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Chemistry: Whiteboarding Problems

Students struggled with the stoich problems I left them yesterday, so we took some time to go through the first part of one. I tried to be very explicit and specific in bringing up previous labs or activities that used each skill, and that seemed to help students make connections. Students then continued the problem in small groups working on whiteboards. I need to do more whiteboarding problems in this class; the whiteboards really helped students function as a cohesive group, which is really not surprising.

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Day 82: Mapping Electric Potential & Stoich Practice

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Physics: Mapping Electric Potential

Students used Plotly to make contour maps of the data they collected yesterday. I was out on a field trip, so students followed along with a video I made last year. Based on my sub’s report and what the students I ran into said, the video went much more smoothly than when I’ve tried to give live instruction since students could pause and rewind the video to make it go at their pace. Tomorrow, we’ll do some talking about the results.

Electric Potential in a Water Tray- Pennies in Corners (1)

Chemistry: Stoich Practice

I left students two stoich problems broken up to try and help them think conceptually about the process. According to my sub, students struggled with the problems. Tomorrow, I’m planning to spend a lot of class time discussing the problems.

Day 81: Mapping Electric Potential & Stoich

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Physics: Mapping Electric Potential

Students collected data for the Modeling Physics lab on mapping electric potential.

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Chemistry: Stoich

Students finished the lab from Friday. The idea was to work through a stoichiometry problem, using nuts, bolts, and washers to represent atoms. My goal was to get students to think concretely about the process so that the math would make more sense. While students got closer to understanding the process, almost none of them saw the connection between their materials and the math they were doing. I need to re-work some of the questions and directions to explicitly prompt them to use the materials at key points. I also need to think about how I could have students use the manipulatives to answer the most frequent questions I got, so I can give them that nudge next time instead of focusing on the math.

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Day 80: Projectile Launchers & Return to Stoich

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Physics: Projectile Launchers

Students tested the final versions of their projectile launchers today. I picked random target distances in three different ranges, and groups had to pick one target to try and hit. I really enjoyed seeing the creativity in the materials students used. On group built a basic launcher out of K’Nex and decided to take a slushie break as they tried to come up with something to hold the ping pong ball, only to realize the lids from their slushies were the perfect size and shape. They also decided an adjustable height would make it easier to hit the target and came up with attaching the launcher to a music stand.

While students applied a lot of good data analysis to the project, the connections to energy and projectile motion weren’t as strong as I’d like, which I think has a lot to do with the way I broke up the project. I tried to squeeze energy into the two weeks between the start of tri 2 and winter break, and the project ended up bleeding into electrostatics. Next year, I may try starting the project with projectile motion, then working the redesign into the energy unit. There will be some administrative challenges, since the project will be split across two terms and a lot of students switch class periods, but I think it will pay off with students seeing a stronger connection to the physics content.

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Music stand, K’Nex, and a slushie lid

Chemistry: Return to Stoich

The next unit covers percent yield and limiting reagents, but scores were low enough on the assessment I gave before winter break that I want to revisit stoichiometry before we try any percent yield problems. Today, students started a lab to predict masses for an imaginary reaction using nuts, bolts, and washers in place of actual atoms. I wanted to give them something they could manipulate and measure very directly to get some conceptual understanding of stoich before we try any more problems. I wrote the lab with the intention of helping students work piece by piece through the process and questions frequently rely on information from a previous answer. A few groups, I think in an effort to be collaborative, tried to divide and conquer, and the students working on the later portions of the lab found they were stuck. Before we finish the lab next week, I’m planning to have a conversation with them about the shortfalls of the divide and conquer strategy and to come up with some more effective collaboration strategies.

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Day 79: Electric Field Lines & Energy in Reactions

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Physics: Electric Field Lines

Students whiteboarded their answers to yesterday’s worksheet. The time we spent on vector addition diagrams with forces paid off as students were very successful adapting those to make sense of electric fields.

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Chemistry: Energy in Reactions

We started with a “mini-lab” to give students some first-hand, tactile experience with endothermic and exothermic reactions. After that, I tried having them sketch bar charts for those reactions, but it was clear I hadn’t done enough to help them understand what energy is, let alone the different types of energy that will appear in a chemical reaction, so the bar charts ended up a confusing abstraction for most students. I need to rethink how I approach reaction types next time to give students a better foundation in energy.

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Day 78: Electric Field Lines & Energy in Reactions

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Physics: Electric Fields

Students built off what they can see in the PhET Charges & Fields to develop the idea of what electric field lines represent. Students mostly got into trouble when they  thought their answers were too obvious and tried to come up with something more complicated.

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Chemistry: Endothermic & Exothermic Reactions

To introduce endothermic and exothermic reactions, we broke the terms down and talked about other words with the “therm” root and what that says about what these new terms might mean. Students then did some reading about endothermic and exothermic reactions. While the textbook doesn’t emphasize the role of energy in these reactions, I tried to bring that out in the short discussion after the reading.

Day 77: Board Meeting & Activity Series

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Physics: Electric Fields Board Meeting

Students whiteboarded their graphs from yesterday’s electric fields simulation. I was really pleased with how quick students were to bring up Coulomb’s Law as a way to check if their relationships made sense. There was also some good discussion about why linearization is useful, where several groups shared their initial attempt to linearize using a purely inverse (rather than inverse-square) relationship between field strength and distance.

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Chemistry: Activity Series

Students dropped four different metals into four different solutions to see how many times each metal reacted. They were able to rank the metals in a crude activity series, then we looked at how that activity series could explain which solutions each metal reacted with.

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Day 76: Electric Fields & Interpreting Reactions

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Physics: Electric Fields

Students used PhET’s Charges and Fields sim to look at how the size of a charge and the distance from a charge impact the magnitude of an electric field. Tomorrow, we’ll get from their data to the equation for electric field strength and draw some parallels between electric fields and gravitational fields.

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Chemistry: Interpreting Reaction Equations

Students worked on using chemical equations to determine which of the five reaction types was happening. I was really pleased by the way students started to talk about what is actually happening in the reaction, rather than just talking about the abstractions represented in the equation.

Day 75: Coulomb’s Law & Mystery Tube

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Physics: Coulomb’s Law

Students worked a few problems using Coulomb’s Law. I was really pleased to see how smoothly students integrated what they’d learned about Newton’s Laws back in November with the new concept. Something about today lead several students to say they feel like they finally understand how to learn physics, which was great to hear.

Chemistry: Mystery Tubes

After this week’s lab, I wanted to spend some time on observations, inferences, and the nature of science. We talked a bit about the difference between observations and inferences, and what makes a good example of each, then asked them to make some observations and inferences about a few photographs. A photo of a crying baby lead to some great discussion when I started to list the crying under observations and several students disagreed and proposed some other explanations for the baby’s facial expression. I love it when students are confident enough in their ideas and comfortable enough in the classroom to challenge me. After the photos, I got out a pair of “Mystery Tubes” and asked students to try to come up with some inferences about what’s inside the tube, then use toilet paper tubes and string to test their inferences. There was some great discussion as students proposed ideas, then challenged what their peers were thinking, always talking about the evidence they have. Going forward, the challenge will be to make sure students are bringing those same skills and enthusiasm to more standard chemistry labs.

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