Wish me luck. I start dimensional analysis today. For some (like many of us), it just makes sense. And for others (like many, many of your students) it seems random. Some students have a hard time creating a plan or a roadmap of where they are trying to go. This year I am trying something new. I am making dimensional analysis visual before it’s mathematical. Let me explain.
Before I even start talking about conversions, I am going to hand each table group a small set of cards. They aren’t fancy, just sharpie and paper. I will have them pull out two particular cards, the first and last one. In this example, it is star over 1 and box over 1.
The way the puzzle works is that in order to turn star into box, they have to match shapes, top and bottom. If a shape matches, it cancels. The challenge will be for the students to create a chain that connects star and box.
The goal is that the students begin to look at a more complete picture of a path from beginning to end. Doing it visually first, removes some of the math-aphobia, particularly from my general chemistry students.
After they have completed the simple puzzle, I will ask them why they “converted” into castle. (Yes, that is a castle. Yes, I am going to use this again when introducing stoichiometry and the mole kingdom. And yes, that is the best castle I can draw.) Their answer will be because it’s the only shape that connected circle and square. It was the doorway.
Currently, on my door into the hall, I have taped two metric units on the inside; 454 g and 2.54 cm. I am trying to create yet another visual cue for how dimensional analysis works. Once students recognize that there needs to be a connector or a doorway, I want them to visually see the doorways that we will be using. On the outside of the door are taped 1 pound and 1 inch. Because out in the hall, everyone speaks the English system. But inside we speak metric. The only connection is that door.
Now students begin to see the correlation from the puzzle game to the room. In order to convert from metric to English, we have to make it to the door. Just like in the puzzle, they had to make it to the castle. Then they have to walk through the door which is a particular set ratio. For my class, the students write down the metric-English doorways on their Stoich Steps (this is a reference sheet that they will use all year on quizzes and tests that you can download here). 1 inch / 2.54 cm and 1 pound / 454 g. Just like the puzzle, they have to make it to the doorway. Then they have to walk through the doorway.
It's a lesson that will only take minutes. But in those minutes, students that think differently will have an opportunity to create a much more visual and logical plan to dive into dimensional analysis. Reducing the fear and anxiety over creating a plan for changing units will pay off both today and down the road in stoichiometry.
Want a different way for students to think about moles? Periodic trends? Ionic formulas? Try Stoich Decks games in the classroom. They are designed to be part of the curriculum, not an add-on. Check them out today.
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