Stoichiometry

Day 141: Free Response, Longitudinal Waves, & Limiting Reactant Lab

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AP Physics: Free Response

Students whiteboarded some released free-response problems, then reviewed their work with a scoring guide and presented to the rest of the class. We spent some time discussing the patterns in the scoring guide, like making sure you articulate every detail to get all the points. I especially made sure we spent some time discussing the experimental design problem from this set; a lot of students have been coming up with fairly complicated experiments on these problems, so we looked at the kind of simple approaches that can be very effective.

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Physics: Longitudinal Waves

Students played with slinkies to see if what we’ve figured out about transverse waves so far works for longitudinal. A lot of groups got tripped up by the wording of my question on whether the relationship we previously found between wavelength and frequency still works. I think a lot of it is I’m having trouble getting across to students this year what I mean by a relationship between two variables.

Chemistry Essentials: Limiting Reactants Lab

Students did a reaction between aluminum foil and a solution of copper (II) chloride dihydrate. I assigned each group to use a different set of masses for their reactants so that different groups would have different limiting reactants. There was a pretty dramatic difference in the color of the solution at the end, which made for a pretty cool visual of the limiting reactant. Time got tight, though; next time, I need to spend about half a period pre-labbing, then get students actually doing the lab the next day. For this course, it could also be good to simply ask students to come up with an explanation for why different groups have different colored solutions without asking students to do the number crunching.

 

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-Y

Day 140: Post-Test & Speed Dating

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AP Physics & Physics: Post Test

Both of my physics classes took the FCI post-test. Not surprisingly, the scores in my AP class were much higher, but there was significant growth from the majority of the students in both courses.

Chemistry Essentials: Speed Dating

Students did some whiteboard speed dating on limiting reactant problems. The speed dating had mixed results; there were a lot of mistakes finding the molar mass, and most students weren’t comfortable changing the previous group’s work. This did lead into some good discussion on the value of showing your work and what clear work looks like. I also ended up working an example, which several students had requested at the start of the hour, but after the speed dating, I was able to address specific issues and challenges and students were more engaged than I think they would have been early on.

Day 139: Free Response, Standing Waves, & Whiteboarding

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AP Physics: Free Response

We are starting to review proper for the AP Physics 1 exam. Today, I gave students the 2015 free response and asked each group to sign up for a problem they will become the experts on. There was lots of good discussion about reading carefully and parsing what the question is really asking.

Physics: Standing Waves

We got out the wave generator and a strobe light to get a few more ideas in place about standing waves. The strobe light helped a lot with talking about the particle motion since it became possible to track the movement of the string.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-Y

Chemistry Essentials: Whiteboarding

We spent some time whiteboarding yesterday’s problems. We spent a lot of time on the first problem, which had nice whole number mole ratios, so we could look at how the particle diagrams show what math needs to be done.

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Day 138: Tic Tac Bounce, Board Meeting, & Problems

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AP Physics: Tic Tac Bounce

As part of the toilet paper practical, I asked students to calculate the final velocity of their unwinding roll using a v-t graph and using an LOL diagram. The discrepancy between the two velocities prompted some good discussion, which lead nicely into Kelly O’Shea’s bouncing Tic Tac demo and the idea of rotational kinetic energy.

Physics: Board Meeting

Students whiteboarded their data from the snakey spring lab. There were still more groups than I’d like who had results that were definitely not an inverse relationship between wavelength and frequency. The big problem seems to be in finding the frequency; we haven’t made much use of that term, so I think students are not attaching much conceptual meaning to it, in spite of the pre-lab discussions. We also didn’t do as much as I usually do with position vs. time graphs for simple harmonic motion, which seems to be making wavelength a tough concept to grasp. Next year, I need to rethink my unit on springs and pendulums to build a better foundation.

Chemistry Essentials: Limiting Reactant Problems

Students worked on some written limiting reactant problems. It was a much tougher leap than in past years; this class isn’t as comfortable with using particle diagrams as a tool for thinking, and I think that made limiting reactants feel more like something new than a natural step in what we’ve been doing.

Day 137: Toilet Paper Practical, Snakey Springs, & Limiting Reactant Hardware

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AP Physics: Toilet Paper

Students finished working on the lab practical we started yesterday. Students did a lot of connecting ideas, which was great. I added a question asking students to calculate the final velocity of their unrolling roll using the velocity time graph and using energy, which I’m hoping to use to introduce rotational kinetic energy tomorrow.

Physics: Snakey Springs

My plan was to whiteboard yesterday’s lab, but most groups had either a linear or quadratic relationship between wavelength and frequency; a lot of students seemed distracted during yesterday’s pre-lab discussion, and I should have taken the time to bring their focus back rather than plowing ahead. We took a few minutes to talk about whether the graphs groups have make sense, then revisited the pre-lab discussion and re-did the data collection. I’ve had some other labs this tri we needed to re-do because of poor results, so I need to think about how to do a better job of making sure the lab goes well the first time around.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-Y

Turns out my heavy ring stands work well for holding one end of a snakey spring

Chemistry Essentials: Limiting Reactants Hardware

We revisited the nuts, bolts, and washers and the “reaction” used to introduce stoichiometry to explore more with limiting reactants. I had a few students who were bothered that there isn’t a simple rule they can always use to immediately identify the limiting reactant, but they were still able to see the kinds of approaches I wanted them to.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-Y

Day 136: Toilet Paper, Snakey Springs, & Limiting Reactants

/ Marta R. Stoeckel / 1 Comment

AP Physics: Toilet Paper

I started by having students whiteboard some model summaries. I started with linear motion, then asked students to add the angular version of each representation. This seemed to help students draw connections between linear and angular motion. Afterward, students started working on a lab practical to predict where to start an unrolling roll of toilet paper so it hits the ground at the same time as a toilet paper roll dropped from a given height.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-Y

Physics: Snakey Springs

To introduce waves, students played around with snakey springs to look for ways to change the behavior of the waves and get some data for a relationship between wavelength and frequency. Today was one of the first days it was 60 degrees all day and there wasn’t much snow on the ground, so I took the lab outside and a lot of students used sidewalk chalk to help with their measurements. There were also some good observations of the shadows; one group making cycloid waves noticed their shadow looked the same as the shadow for 2D waves.

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Chemistry Essentials: Limiting Reatants

Students used a PhET simulation to start building some ideas about limiting reactants. The class was much rowdier than usual; the class meets the last period of the day, and I think the nice weather was making a lot of them restless. The concrete visualizations did seem to help a lot of students start making sense of limiting reactants.

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Day 135: Whiteboarding

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AP Physics: Angular Momentum

Students whiteboarded yesterday’s problems. There was a lot of good discussion; I think rotation is starting to click for a lot of students. I also did a few demos, including one with an RC motorcycle inspired by a Evel Knievel statement prior to a jump over the Snake River Canyon that his biggest fear was accidentally letting go of the gas while in mid-air.

 

Physics: Oscillating Particle Whiteboarding

Students whiteboarded yesterday’s problems. The connections between the math and the big ideas seem to be clicking for a lot of students. One of the questions we discussed is whether the angle of a ramp should affect the period of a cart oscillating on a spring, so I set up the demonstration.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-Y

Chemistry Essentials: Percent Yield 

I kept the whiteboarding pretty short since a quiz on percent yield was also on deck for today and the para working with the class had let me know that students had done very well with the problems. We targeted a couple of trouble spots, like a problem where a lot of students dropped a decimal point yesterday, leading to over 800% yield. I was really pleased that students recognized why that was not a reasonable answer, even if they had trouble finding the error.

Day 134: Problems Galore

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I had a sub today, so no pictures. All three of my classes worked on problems.

AP Physics: Angular Momentum

I gave students some angular momentum problems. Its been a while since we hit linear momentum hard, so I’ll be curious to see how it went shaking the dust off and translating to angular scenarios. I also threw in some torque problems; on the last quiz, a lot of students weren’t sure what an extended free-body diagram is, so that is something I needed to make sure to revisit.

Physics: Springs & Pendulums

Students did some problems using the equations for the period of a spring and period of a pendulum. Earlier this week, some students were having trouble distinguishing the two formulas, but I think the lab practicals helped. I’m hoping that shows up in how the problems went.

Chemistry Essentials: Percent Yield

Students did some percent yield problems. They look very similar to the stoichiometry problems we’ve been doing, with a step added at the end to calculate percent yield. When I got to school for parent-teacher conferences, I was able to connect with my sub and the para who supports the class, and both told me the problems went very well for the majority of students; they are seeing the connections between what we’ve done previously and the new material. The para also reminded me I need to crack down on students showing their work; a lot of students are frustrated because looking back at their old work isn’t helpful, but they don’t yet see that writing out their work would change that.

Day 133: Board Meeting, Pendulum Practical, & Percent Yield

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AP Physics: Board Meeting

Students whiteboarded their results from yesterday’s Pivot Interactives activity. Students spent a lot of their time yesterday on whether the location of the collision affects whether linear momentum was conserved, but had a lot of interesting approaches and good discussion about that question. For the portions of the activity specific to angular momentum, I ended up much more teacher-directed than I like since I will be out tomorrow and am feeling the time crunch of the looming AP exam.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-Y

Physics: Pendulum Practical

Students finished yesterday’s practical, then were tasked with finding the period of a pendulum without using a ruler or meterstick. Not surprisingly, most students declared the pendulum practical was much easier than the spring one.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-Y

Chemistry Essentials: Percent Yield

Students predicted how much carbon dioxide should be produced in a reaction between baking soda and hydrochloric acid, then found the percent yield by measuring how much mass was “lost” during their reaction. I like that this lab circles back to conservation of mass to measure the mass of gas produced, but a lot of students had trouble connecting the lab to the stoichiometry problems we’ve done, so I need to think about how the layout and wording of the lab may be making those connections more difficult.

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Day 132: Angular Momentum, Lab Practical, & Popcorn

/ Marta R. Stoeckel / 1 Comment

We had a snow day yesterday. Students (and teachers!) are getting restless for spring; after seeing the grass and even a few dandelions sprout last week, it was tough to get another 18 inches of snow.

AP Physics: Angular Momentum

Students used Pivot Interactives to explore angular momentum using a collision between a marble and a block. I started by having students determine whether the location of the impact changed whether linear momentum was conserved, which lead to some great conversations. A few students needed some reminders about linear momentum, but that wasn’t surprising given I haven’t done a great job of spiraling back to earlier topics this term.

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Physics: Lab Practical

I gave students some springs we haven’t worked with yet and asked them to make a graph with period on one axis where the slope could be used to find the spring constant. This was the first time I’ve had students go backwards from an equation to picking a graph to make, so it was a little tricky, but students had some great conversations about the relationships they were working with. Next year, I’d like to try to get more lab practicals that focus on graphs rather than just calculations.

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Chemistry Essentials: Popcorn

Students determined the percent yield for a bag of popcorn by finding how many kernels remained unpopped. It was messy, but it gave students a nice, concrete foundation for what percent yield means. It also came up in the discussion why some of the popcorn kernels didn’t pop, which could make this lab something to come back to when students want to blame less than 100% yield on doing the lab wrong or (shudder) human error.

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