Unit 2: Energy and States of Matter (Duration: ~ 3 weeks, or 13 class meetings)
This unit began relatively normally, with diffusion demos and storyboards. We watched the Eureka! videos, and we discussed measuring temperature, and how to represent cold and hot particles in motion. We had a great discussion on our particle representations, when forced to remove all words from our whiteboards.
After a discussion of thermal expansion of liquids and solids, rather than moving on to pressure and gases, we went right to heat and temperature. Continuing with the Icy Hot Lab, we introduced energy bar charts to describe the changes qualitatively.
For time reasons, we did not complete the Lauric acid activity, but one valuable addition was a worksheet for students to practice drawing temperature-time graphs for substances other than water. We finished with quantitative calculations for phase and temperature changes.
This change in sequence seemed natural. I will definitely repeat next year.
I’m currently in my 8th year of teaching, 7th year of teaching Chemistry, and 5th year as a modeler. It is not an exaggeration to say that my experience with modeling has changed my entire teaching philosophy, and the way that I relate with students. It has also had an impact on how I teach chemistry not only at the introductory level, but also in my AP-level courses.
Starting this year at a new school, with no other modelers in the department, I planned to depart from the modeling framework. After about a week and a half of getting to know the kids and where they were, I quickly reverted back to my old ways. I’ve made some modifications, additions and omissions, that have worked well so far, and will probably continue to use moving forward.
Here’s an overview of my first unit.
Unit 1: Chemical Foundations (Duration: ~3 weeks, or 13 class meetings)
Introductory Activity: #chemchat
This activity had a few goals:
- Give the students an opportunity to talk about what they did this summer (which they are always dying to do on day one).
- Get to know something new about their classmates (and for me, to get to know them).
- To see what they already know (pre-assessment).
The students have almost all come from physics the year before, some conceptual, and some computational, so there was a wide range of background in science skills and practices. So each station was devoted to a specific skill or content knowledge.
- lab equipment
- making observations, forming a hypothesis
- making measurements and metric conversions
- dimensional analysis
- prefixes and suffixes
- chemical and physical properties
- lab safety
This was a successful activity, but I don’t think I will need to use it again.
I usually show clips from Flinn’s “Starting with Safety video,” but this year had students watch this video for homework, and list as many safety violations as they could find. On average, each class found around 24. From this, we organized the violations into groups (personal protection, handling chemicals, and common sense). We added to the list as needed, and took a safety tour through the lab space.
Water + baking soda + calcium chloride + phenol red = lots of observations. After one trial, we compared our observations as a class. Then, we sought to determine which substances were responsible for which of the changes we observed. Each lab table “dropped” one of the substances, and recorded new observations. We then made a HUGE data table on the front board. where each group reported out which changes they observed in their trials. Using the shared data table, students answered the following questions in pairs:
- Which ingredient is responsible for the rise in temperature? Explain.
- Which ingredient is responsible for the drop in temperature? Explain.
- Which ingredient is responsible for the color changes? Explain.
- Which ingredients are required to produce all of the changes observed in the initial baggie?
- Summarize the four signs of a chemical reaction, and cite 1 trial (besides the initial) where that sign was observable.
While the main goal of this was to give students experience with collaboration and analyzing data, it is continuing to pay off in later units.
This lesson wasn’t too different from the “reading scales” lessons in the modeling chemistry unit, but since the students had already learned significant figures in physics, my emphasis was on uncertainty in measurements. We did a quick lab activity where we practiced this skill. Students then completed the “Reading Scales” modeling worksheet for homework.
The next day, we did another measurement activity. We did a similar activity when I was a TA for a general chemistry lab back in the day. The goal here is to investigate precision and accuracy of the tools that we use. The following day, we shared average percent deviations for each scenario, and had a good discussion about precision and good lab practices. It also gave us clear data for using a graduated cylinder over a beaker for measuring volume.
This has “stuck” with most of my students (at least so far), so it was definitely a worthwhile activity.
Mass and Volume (and the rest)
It’s around this time that I made the gradual switch back to the modeling curriculum. While we didn’t go back to do the mass and change activity, we began to incorporate particle-level representations here. I didn’t do as much emphasis on graphical analysis, in terms of y-intercept and correlation, since we were graphing by hand at this point. Using relative densities of solids, liquids and gases, were able to build a sufficient model to move forward.
Next year, I definitely hope to include the mass and change activity. Fortunately, students have exposure to both significant figures and dimensional analysis from freshman physics, so I am happy to continue to use that time saved for building measurement skills and good lab practices.
Next up: Energy.
As I headed over to my blog dashboard, I realized it has been almost exactly a year since I last posted. And, funny enough, I am exactly where I left off. I am back at Taft School, this time for a two-week AP chemistry workshop. The main difference is this time I actually will be teaching AP chemistry in the fall.
This is my second round of professional development so far this summer. A few weeks ago I attended an amazing week-long conference at St. Paul’s School. Early in the week, we had some lectures on how students learn, effective strategies to maximize what students learn, and backwards design. In the second half of the week, we applied a bit of what we learned to prepare a full lesson to other participants. One great thing about this conference is that all of the participants were from independent boarding schools. As a group we had a wide variety of experience, some teaching just a few years, others teaching almost a few decades. While I went in skeptical about having a single conference for history, English, foreign language, math and and science, I actually got a lot out of the experience. In fact we were never segregated into our subject areas. I observed and gave feedback on nearly a dozen lessons in spanish, psychology, English and science, and feedback on my lesson from humanities teachers on my own lesson was most valuable. And as an added bonus, I got to know a few of my new colleagues.
Later this month, I will be going to ChemEd 2015, and leading a workshop (along with Laura Slocum and Brenda Royce) on Stoichiometry.
A very busy summer indeed.
All textbooks are not created equal (though a few are very similar)
As is typical in these sorts of workshops, I ended up with about 500 lbs of free textbooks. In addition to the typical (Zumdahl, Brown/LeMay) I got to look at a few that I hadn’t heard of or considered before. My favorite among the shiny doorstops was Gilbert’s. However, the book that I’ll probably read the most myself is Principles of Chemistry by Michael Munowitz. He’s a science writer, and clearly has a passion for chemistry, that comes through in his writing. Unlike the others, it is written for those who want to gain a deep, conceptual understanding of chemistry, rather than focusing on problem solving techniques. If you teach chemistry, you should definitely add this book to your shelf. It isn’t great for intro-level high school students, or even most AP students, but it will help you as a teacher find more and better ways to explain the more abstract aspects of chemistry. I can’t find sample pages online, but here’s a review from JChemEd that will give you more info on it. Here’s a glimpse, from chapter 3 (Prototypical Reactions)
“Humpty Dumpty’s great fall tells it all. He falls from the wall and breaks into pieces, never to be mended. He goes from high gravitational energy to low, and he changes from a single, orderly arrangement into scattered, disordered bits and pieces. Lower energy. Higher entropy. Lower free energy.
“Molecules, like Humpty Dumpty, also take the easy road, the road that leads to less energy and more disorder. Only if the reactants can decrease their free energy will a reaction occur on its own, for only then is the transformation profitable. The larger the drop in free energy, the more thoroughly do the reactants combine to form products. A lower free energy is the thermodynamic profit that nature demands to convert A and B into C and D.”
That’s it for the workshop. I’ve left a few things out. There were a couple of really good labs that I will definitely do this year. I’ll post more on the baggie lab and also on the thermodynamics lab in a later post (hopefully while at BCCE). I hoped that we’d have time to share resources with the other participants, but the workshop was a little too short.
I, again, definitely recommend taking an AP workshop at
Hogwarts Taft TEC. It’s no way as fulfilling as a good modeling workshop, but it is a pretty good way to spend a week or two of your summer. Just be sure to bring an extra suitcase.
Modeling Chemistry (or physics, or bio) seems to be the perfect prep for the new AP class
When looking at the College Board’s recommendations for improving performance on this year’s Free Response Questions, some repeated themes include
- have students draw particle views of…
- distinguish between descriptions and explanations
- have students describe in words what they observe
- have students explain what they believe is occurring (but cannot see) in terms of both chemical principles and particle-level diagrams
- no naked numbers
- algorithmic calculations are okay only if accompanied by conceptual understanding
Erica Posthuma-Adams wrote an article in the Journal of Chemical Education about modeling chemistry and AP Science Practices.
Your students lack time management skills.
Which is why 57% of test takers left the last Free Response Question blank.
While you should definitely teach better time management skills, they may add a reading period in next year’s exam.
They 2015 exam is already written, so there can’t be major changes to it at this point.