When Chemistry Becomes Math Class

At a convention I was at the presenter told the following anecdote:

A group of science educators wanted to see what students’ impressions were of Chemistry class. Immediately before the first day of class, the evaluators asked the students to describe what they thought Chemistry was in three words of less. As they expected, words like fire, explosions, reactions, chemicals, dangerous were among those at the top of the list. At the end of the first quarter, the evaluators returned and asked the same question and were surprised at how the students’ idea of chemistry had changed. Now words like math class, boring, work were at the top and nowhere could be found words about science.
One of my biggest complaints about typical Chemistry curricula and textbooks are that they start with significant figures, scientific notation and conversions, very little of which has no impact on Chemical principles or the understanding of Chemistry in general, but rather only how students report their answers. I decided to start with actual Chemistry and teach naming and forming ionic compounds. We then worked backward through the curriculum, through the Periodic Table, basic Atomic Structure, and now we are in the dreaded sig figs and scientific notation.
Since I am very activity driven in class I wanted this to be more than notes and worksheets. I trolled Googled looking for “innovative significant figures activity.” It is amazing what some people call innovative. Some things I found were webquests, an “interactive” website that was a just a digital worksheet, and an activity that required students to count popcorn kernels. I decided to just make my own.

I went through my sons’ toys and grabbed random objects as seen below.

Each student received either a 6 in ruler, 12 in ruler or a meter stick as they walked in the classroom. I then asked them to measure the length of the object in both centimeter and inches and compared the accuracy of both. This part was fun because I made sure the kids with large objects received small rulers and the ones with small objects got the meter stick.

We then calculated the volume of their object. This led to a lot of questions because we needed to figure out what was the better measurement to use for the calculation. After this, we answered the Essential Question for the day which was “How many of your object will fit into this room?” My room is an odd shape so the class needed to figure out how to find its volume as well as make the measurements of length, width and height with meter sticks.

Once each student calculated the number of their objects that fit in the room (the answer really surprised them as many of them had in the millions or even billions) we needed to discuss accuracy of their answers which is where significant figures came in.

As we just finished the Quarterly where they needed to use significant figures and scientific notation I saw a definite improvement in the scores involving those questions. There were still students who got those questions wrong, but I noticed during the exam students who were clearly recalling the rules we used and, hopefully, the activity.

Was this a fool proof method? Absolutely not. Did we have a lot more fun learning about something so dry as sig figs? Definitely!


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