Chemistry modeling: a recap

I just finished a two-week workshop on Chemistry Modeling. For those of you who aren’t familiar with the modeling methodology, I highly suggest checking out the American Modeling Teachers Association (AMTA). These are some of my thoughts and reflections on this workshop and the chemistry modeling curriculum as a whole.

This workshop was a good introduction to both the modeling methodology and the chemistry modeling curriculum. The chemistry modeling curriculum is fairly recent compared to the physics modeling curriculum, so most of the teachers who are currently using this curriculum haven’t been using it long, but it was great to hear from different teachers who are using this methodology in their different classrooms.

The modeling chemistry curriculum focuses heavily on the particulate nature of matter and introduces kinetic molecular theory in Unit 2. I am still contemplating how this curriculum compares to a more ‘traditional’ chemistry curriculum. Primarily, the amount of content covered is significantly less, but that is true of the physics modeling curriculum as well as any curriculum that is heavily student-centered and based in student inquiry. Additionally, because the chemistry modeling curriculum considers chemistry from a historical view, students are presented with models that must be refined and rethought throughout the year. This results in students using the Thompson model of the atom (‘plum pudding’) for most of the year, as the Bohr model is not necessary to understand and explain the observed phenomena until periodic trends are discussed (also at the end of the year). I’m still considering whether I’m ok with students holding a ‘wrong’ model of the atom for the majority of the year. However, I do like the sequencing of the curriculum because it follows a more logical progression and the topics do build upon each other. The consistent use of particle diagrams would also allow students to connect the macroscale phenomena and symbolic representations with what is occurring on the microscale. After many discussions with fellow chemistry teachers on the ‘triangle’ of chemistry (first proposed by A.H. Johnstone, I believe), I feel like the modeling curriculum will allow students to gain better conceptual understandings of chemistry.

For me, a key take away from this workshop may not be directly tied to the modeling curriculum. The presenters emphasized the use of ‘for every’ language vs. ‘per’ when discussing slopes and ratios. (This idea was from Gary Abud’s presentation at ChemEd in 2011; he has a nice recap on his own blog.) They also pointed out the value of allowing students to use proportional reasoning rather than dimensional analysis in solving problems. Students in high school are often still concrete thinkers, so proportional reasoning makes sense to them whereas dimensional analysis and t-charts may simply be algorithms they use without understanding the concepts. The modeling curriculum uses IFE (Initial/Final/Effect) and BCA (Before/Change/After) tables for gas laws and stoichiometry, respectively, to promote students’ conceptual understanding rather than giving them equations and algorithms that they can use without ever understanding the chemistry. Students can solve gas law and stoichiometry problems without ever being given the ‘official’ gas laws (Boyles’, Charles’, Gay-Lussac’s) or t-charts for gram-gram conversions. These are all aspects of the modeling curriculum that could be used without fully implementing this curriculum. And of course, I see no reason to limit the use of ‘for every’ language to chemistry.

However, several presenters and teachers who have implemented the modeling curriculum piece-meal highly recommended going “all in” if possible. They suggested this simply because it can take the entire year to build the classroom community that is necessary for successful modeling, as so much depends on the Socratic discussions and whiteboard presentations. I would agree that if whiteboarding is going to be a part of the class, it must be interwoven throughout the year. However, some of the activities and strategies could still be used in a more traditional sequence of chemistry. Additionally, many of the labs and activities in the ASU curriculum are currently used by chemistry teachers regardless of their curriculum and/or could be swapped for activities that are currently used. The presenters pointed out specific units that were more conducive to using whatever materials teachers were currently using (e.g., the mole and stoichiometry were two units where they suggested that current materials could be easily modified for a modeling classroom).

During the workshop, we were able to talk to a panel of students who had gone through a year of modeling (either chemistry or physics). This gave me a good idea of how students view modeling, and overall the feedback was very positive. However, most of the panelists were students who enjoyed science and were A-B students. One student who does not consider herself as ‘good’ in science stated that while she didn’t feel like she fully understood chemistry (as in being able to do all the calculations), she felt like she got the concepts. I think she felt like this was a detriment to the modeling curriculum (as she wasn’t able to fully understand the quantitative side of chemistry), but as teachers, we felt like we would be very successful if all of our students were able to get at least a qualitative, conceptual understanding of chemistry. I would have appreciated hearing from students who were in the ‘regular’ track (all of the students were from the ‘advanced’ courses), but these students gave me an idea of how students view modeling compared to their previous science classes. In particular, students in chemistry stated that they enjoyed modeling compared to their biology classes because it was less memorization.

The modeling curriculum also tries to connect energy throughout the chemistry curriculum rather than treating phase change and enthalpy as disparate occurrences. They also encouraged changing the wording used with students to emphasize that energy is the same, it is simply stored in different ‘accounts’. This workshop clarified the modeling worksheet that we analyzed as a data source for our CI in the spring. The modeling curriculum, as a first-year chemistry curriculum, does not consider phase changes when considering energy in chemical reactions to simplify the picture for students. As chemistry teachers, we had many interesting discussions on how to represent energy in the chemical systems using the LOL charts in the modeling curriculum. It was difficult to explain reactions that are rather complex because entropy and enthalpy must both be considered in the energy discussion, and we discussed whether it would be best to leave these reactions out of the curriculum altogether to avoid confusion. I really enjoyed these discussions because they forced us to consider the rationale behind the decisions to include or exclude certain topics in the modeling curriculum. However, the idea of conservation of energy is introduced early (at the point of phase changes) and used in all energy discussions, and I absolutely loved that.

I would love to use this curriculum and see first-hand how students respond to it; however, I won’t be teaching chemistry next year (I signed up for this PD before I started interviewing for jobs). Nevertheless, I will be teaching physics using the modeling curriculum, and the experience with working with this curriculum both as a student and as a teacher will be valuable for my first year of teaching. Additionally, I was able to sit in on the physics workshop for one day, and see some of the similarities and differences between the physics curriculum and the chemistry curriculum. (One major difference was that the physics units all appear to be structured similarly- paradigm lab, model development, model deployment, lab practicum- whereas all of the chemistry units do not involve developing a mathematical model and therefore are structured differently). I also think that the discussions about the use of algorithms vs. promoting student understanding of the content will be important to keep in mind as I teach freshmen who are used to high levels of academic success. I am very excited about trying to use ‘for every’ language rather than ‘per’ for slopes and other proportional relationships (e.g., ‘for every 1 cm3 of water, there is 1 g of water’ rather than ‘water has a density of 1 g/cm3), and I am sure that this has a place in physics as well as in chemistry. The different whiteboarding techniques that were discussed will also be something that I can draw upon in my teaching for next year (groups, individuals, choosing who presents, gallery walks, etc.).

However, a major lingering question that I had after this workshop was how/when to incorporate ‘real life’ into modeling. The chemistry modeling curriculum did not seem to really tie the chemistry back to what students encounter on a day-to-day basis, and therefore I think it would be difficult to get buy-in from students who are typically disengaged from school in general. I wonder if the physics curriculum is similarly distanced. Science is applicable to our students’ everyday lives in a myriad of different ways, but many students see science as something that is ‘other’ from them. The lack of student buy-in could kill implementation of this curriculum. The modeling curriculum presents chemistry in a way that I can really appreciate as a teacher, but how would students who are disengaged from school see this approach?

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