The Choice is Yours: Differentiating the Math of Chemistry


Unlike many chemistry teachers, I don’t teach stoichiometry (the math of chemical reactions) all in one unit. I introduce the mole early in the year with atomic structure and cycle back to the mole concept in every unit I teach. Today I took my second pass at reaction math, incorporating what the students have learned about gas laws in our current unit. Some teachers will tell you that if you don’t show students how to solve these problems, they won’t be able to. I disagree with that and have a couple of years of differentiated lessons to back me up.

When the bell rang, I asked all my students to stand up and come to one side of my classroom. Once they were there, I briefly explained the kind of problems we would solve. Then I described three approaches they could choose from: 

  1. Sit at a table with other people and talk about ways to solve the problems (or ignore everyone and forge ahead without conversation). 
  2. Sit at a table with an iPad loaded with a presentation that will model each type of problem and solve a subsequent one without the model. 
  3. Sit at a table with some manipulatives I made to help get from the start to the finish of the problems.

Then I gave them the opportunity to self-select. Most students ended up where I would have placed them! About half the students sat at the tables with the iPads. About a fourth of the students sat at a table with no resources except each other. The last fourth sat with the manipulatives. The conversations at all the tables were outstanding. At each center, students were having great conversations about why and how they should proceed to an answer. All these conversations would have been lost if I had been the only one modeling.

The manipulatives were just pieces of cardstock with conversion factors on them for each of the problems. They included conversions that students needed and conversions that they didn’t need so they had to choose correct relationships to get from the start to the finish. As a new problem solver, it’s challenging to look at a blank space and figure out which relationship will help solve the problem. The manipulatives took a little guess work out, but still required students to think through the problem and select the right ones. The cards were color-coded for three types of chemistry problems we attacked today. They seemed to genuinely help students see why they sometimes need molar mass but other times they don’t. One student even asked if the manipulatives would be available next week on the quiz.

Two takeaways really stick with me tonight: 

  1. Given a chance and the support to think and talk through problems, my students will successfully do this. The way they help and question each other is awesome. 
  2. When high school teachers say it’s impossible to differentiate, I wonder how often they have tried it.

Today in my class, more students got what they needed. And I did, too, because I was able to wonder around and listen to their terrific progress and touch base and observe students who might struggle. I think all of us – my students and I – learned more today than on many other days this year.

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