Annie Turns from Mad Scientist
to Effective Teacher
by Annie Shao, age 18
Last spring, I graduated from Memorial High School. I will be starting my first semester at the University of Wisconsin-Madison this fall, where I hope to study biochemistry and microbiology. One of my most memorable high school moments, a group demonstration in AP Chemistry class, might have given me a good taste of what I’ll learn about in a college chemistry class.
For this demonstration, each three to four person group had two periods to teach the class about anything related to chemistry. My group and I decided to do some cool reactions in front of the class, and then present the science behind it to. This meant preparing an already complex experiment and presenting it in a way that made sense to our audience.
We settled on the Briggs-Rauscher reaction. It is a clock reaction—meaning it continually changes color on its own. The beaker of solution starts out clear, and then changes from an amber color to blue and back to clear in rapid progression, over and over again. The reaction begins by mixing three different colorless solutions—potassium iodate, hydrogen peroxide, and malonic acid with starch as the color indicator.
The reason the reaction can keep changing colors is a complex mechanism, but basically there are three different sub-reactions that occur, each of which produces iodine at different rates. The iodine turns the solution amber, then promptly reacts with the starch and turns it blue. Some of the sub-reactions consume iodine, and the solution becomes clear. The system uses and replenishes iodide, another chemical, that drives the reactions.
Our demo had a rocky start. The flask of hydrogen peroxide, one of the reactants, was found mysteriously open. My group and I were positive we closed the flask after we made the solution, and my teacher had no idea who could have opened it over the weekend. This was a problem because hydrogen peroxide is unstable and will decompose into oxygen gas and water over time. Keeping the bottle closed helps prevent too much hydrogen peroxide from degrading. I was afraid that, after the two days the hydrogen peroxide was left sitting open, the demo had been ruined before it even started.
There was no time to prepare more chemicals, so I poured the solutions together and said “and we’ll just hope this works.” Fortunately, enough hydrogen peroxide was still left, and my classmates oohed and ahhed at the sudden repeating color changes.
By presenting our demo, my lab partners and I got a taste of what it’s like to teach college material. When I turned around after explaining the Briggs-Rauscher reaction and writing out its equations, I saw a very bewildered class. I didn’t blame them, since it took me a while to understand the reaction myself while I was researching it.
I then took questions from my classmates. With the help of my partners, everyone seemed interested and gained a clearer idea of what was going on in that beaker. At the same time, the reaction actually started to make more sense to me and my lab partners.
Ironically, teaching can be the best learning tool. It’s one thing to learn about something yourself, but it’s another to be able to explain it to other people.