Today is National Math Storytelling Day, an opportunity for us all–though especially the students among us–to get excited about math through stories and games, and help us appreciate all the ways math improves our daily lives.

In honor of National Math Storytelling Day, I want to share a story that illustrates the little unexpected ways that math can influence even the smallest things that you want to accomplish.  We all remember sitting in a math class thinking “When am I ever going to use this?” at some point in our school careers. As we get older, we are often surprised at the answer to that question, as I discovered recently while simply enjoying a hobby of mine.

In my spare time, when I am not knee-deep in the world of education innovation, I am an amateur ceramicist (or, to put it more honestly, I enjoy making still-poorly-shaped cups and bowls out of clay).

At the beginning of this year, I bought six nondescript clear drinking glasses. .. They were mundane tools that served their purpose well, until I realized how fragile they were–they kept breaking from collisions with bowls and plates when I would put them in the sink.

I wanted something sturdier, that had a little more character, but that still held enough water that I could sip for an hour or two without having to make the long journey across my studio apartment to refill it. So I set about making my own perfect drinking cup.

I took measurements of one of my two remaining glass cups to give me the measurements I wanted–17 centimeters tall, with an eight centimeter diameter, tapering slightly (I eyeballed an 80 degree angle). After spending an hour on my first two or three failed attempts, I finally, droplets of sweat dripping down my brow, pulled a cup that was roughly the shape that I wanted and close to the dimensions (15 cm by 7.5 cm). I was ecstatic, and removed it from the wheel to dry.

Classic mistake.

Since clay contains so much moisture, it shrinks as it dries by as much as 20%. Moreover, you usually need to cut at least a little bit off the bottom to make sure the pot sits level. Which meant that the final product was something like 13 cm by 5 cm (and not nearly enough for my water consumption needs–though still decent for a cocktail):

This meant that I had to use the percent change formula to determine what size my cup would need to be when still wet:

% change = ([new number – initial number] / initial number) x 100

Using 20% as a rough estimate of shrinkage, I got the following formula:

20 = ([y-17] / 17) x 100

Using algebra to solve for y, I was able to determine that my cup, when wet, needed to measure 20.4 cm tall in order to shrink to 17 cm (I called it 21 to account for trimming the foot to flatten it out). Using a similar process for width, I determined that it needed to be 9.6 cm wide. When all was said and done, I had a new cup that I have been able to thoroughly enjoy using for the last six months:

While this may not be the most “every day” occurrence, it nonetheless serves as a great reminder that the ability to reason mathematically is very important for me to be able to achieve my goals.

So that’s my #MathStoryTellingDay story–what’s yours? Tweet us @Getting_Smart!

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Erik manages projects for Getting Smart’s strategic advisory partnerships. With a system-oriented outlook and a background in marketing and communication, he oversees the details that ensure our partners’ initiatives are powerful and effective. Follow him on Twitter @ErkDay.