Chemistry Essentials

Day 94: TIPERs & Percent Composition

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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.

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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

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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.

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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

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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.

circuit sim

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.

Day 91: Real Life Circuits & Energy in Equilibrium

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Physics: Real Life Circuits

Continuing the circuit patterns set of labs from the PUM curriculum, students used power supplies and resistors to build series circuits and test the patterns they found in the simulation yesterday. Class ended with each group summarizing their rules on a whiteboard. Several groups used proportions to come up with a rule for how much potential difference goes to each resistor; for next year, I want to think about the questions I’m asking to try and get more groups to take a similar leap.

 

Chemistry: Energy in Equilibrium

Students did a short reading from the book to look at the role energy plays in chemical equilibrium and to help explain some of the results in yesterday’s lab. It also ended up being a nice set-up for the reaction rates lab we’ll be doing tomorrow.

Day 90: Circuit Patterns & Disturbing Equilibrium

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Physics: Circuit Patterns

Today, students started working on a series of labs based on the circuit patterns activities from the PUM curriculum. Today, students built series circuits in PhET’s circuit construction kit, measured the current and potential difference at each element, and started looking for patterns in their results. When using the voltmeter, I was pleased by how many students went back to a lab we’d done moving the ground wire of the multimeter to help explain why some voltages were negative, along with what that negative voltage means. Tomorrow, we’ll pull out the power supplies and resistors to see if their patterns work in the real world.

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Chemistry: Disturbing Equilibrium

Students played with moving a reversible reaction out of equilibrium. After mixing Fe(NO3)3 and KSCN solutions in several different test tubes. Once the reaction was in equilibrium, they tried something different, such as changing the concentration or putting the test tube into a water bath, to and observed the results.

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Day 89: Cost Effectiveness of Light Bulbs & Vocab Intro

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Physics: Cost Effectiveness of Light Bulbs

After a brief introduction to electric power, I tasked students with figuring out which of several light bulbs is the most cost effective. I provided them with the cost and estimated lifetime for each bulb and the current rate the local electric company is charging, along with some Kill-A-Watts they could use to take some measurements.

Calculated costs to run for 15,000 hours
Calculated costs per day

Chemistry: Reversible Reactions

After a quiz on limiting reactants, students used the textbook to start defining reversible reaction and equilibrium.

Day 88: Ohm’s Law & Limiting Reactants

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Physics: Ohm’s Law

Students wrapped up using the PhET circuit construction kit to develop Ohm’s Law. Students were able to pretty easily reason out the formula based on their graphs. Looking back, I wish I’d had students put their experimental conditions and equations on the boards, as well. I usually try to keep the boards pretty simple since I have some big classes, but I think that information would have added a lot of value to the conversation in this case.

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Chemistry: Limiting Reactant Practice

Today, students did some limiting reactant problems where the given and desired information is in grams, rather than moles. I was really pleased at how easily most of them worked through the problems. A lot of my students were struggling to connect ideas between different days earlier in the trimester, so it was great to see how many readily pulled out earlier skills and problem solving strategies to help today. I also saw a big jump in the quality of the questions I’m getting from my students; one student in particular was really focusing on the why when she was talking to me, when in the past she seemed most interested in getting something to write down. I’ve been having a lot of conversations with this class about how learning works and sharing why I do things the way I do, and I’m hoping I can get students to continue with the things I saw today.

Day 87: Ohm’s Law & Limiting Reactants

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Physics: Ohm’s Law

Students used PhET’s circuit construction kit to do a short activity based on the PUM materials to help orient them to the sim, then started looking for a relationship between current and potential difference. I loved it when, during the orientation activity, several groups got curious about the mysterious resistors in the kit, and immediately tried adding them to a circuit to see what they do, without any prompting or intervention on my part. There was also some great discussion and debate in one class about what exactly the blue dots represent. There were also many attempts to electrocute the dog.

dog circuit

Chemistry: Limiting Reactants

After a short percent yield quiz, we had some class discussion to formalize what students found in yesterday’s PhET sim on limiting reactants. I picked some reactant quantities for one of the reactions in the simulation, then had students get into groups and try to predict what they would produce and what the leftovers would be. Before students went to their groups, we had some conversation about what I was looking for. I tried to emphasize that I wasn’t after right answers; instead, I wanted them to share different approaches so we could decide on some useful ways to think about this kind of problem. There was a nice mix of students who focused on the equation given for the reaction and students who sketched diagrams.

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Day 86: Intro to Circuits & Limiting Reactants

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Physics: Intro to Circuits

I gave each group a bag with a mix of various items and asked them to use those items to try and light up an LED. In the past, I’ve told students their task is to light up the bulb, but they should keep track of what doesn’t work. This year, I was more conscious of stating the goal was simply to document what does and does not work so we could look for patterns, and I was much happier with how the exploration went. This was also the first time I used LEDs for this lab, instead of miniature incandescent light bulbs, and I liked the opportunity to reinforce that current has a direction. As an added bonus, the LEDs I have required two AA batteries, which gave the students more options to try. We wrapped up by watching a short excerpt from from the Private Universe series of MIT and Harvard grads trying a similar task.

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Chemistry: Limiting Reactants

Students worked through PhET’s Reactants, Products, and Leftovers simulation to introduce the idea of limiting reactants. I found a lot of students were looking for confirmation that their answers were right, even when the simulation showed the answer. When I talk to many of them, it sounds like they’ve gotten into the habit of assuming they are wrong in school. I need to continue to work on building a culture where my students feel like their ideas have value and to work on strategies to help students analyze their answers, right or wrong.

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Day 85: Whiteboarding & Percent Yield

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Physics: Whiteboarding

Students whiteboarded their answers to Friday’s questions. There were a few questions where students had some good discussion and connected some questions back to the lab where they’d mapped electric potential. I still need to work on getting students to talk to each other more than they talk to me.

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Chemistry: Percent Yield

Students worked on some problems calculating percent yield. While they can do the calculations pretty easily, the concept seems pretty abstract to them. I need to find a good lab to make percent yield more concrete.