Wisconsin college professor uses knitting to teach math
Meg Jones Milwaukee Journal Sentinel USA TODAY NETWORK – WISCONSIN
KENOSHA – Few people look at a ball of yarn and a pair of knitting needles and think, well, here’s a math problem waiting to be solved.
Sara Jensen does.
Before she was a mathematician, before she earned a doctorate in abstract algebra at the University of Wisconsin-Madison, before she began teaching math at Carthage College in Kenosha, Jensen was a little girl learning to knit from her grandmother.
Like many who learned the craft from an older family member, Jensen knitted for a while, then stopped before taking up the hobby again as an adult.
But Jensen is also a math teacher and a couple of years ago she thought it would be cool to use knitting to teach math.
Though mathematicians and math teachers may have a reputation of being dry, dull and boring, Jensen is trying to make math interesting in an unconventional way.
No calculators, no equations on chalkboards, no textbooks. Just plenty of yarn and knitting needles.
“This class is a way for math to be creative,” Jensen said. “I think there’s room for creativity and discovering things in mathematics.”
There was no shortage of students signing up for Jensen’s mathematical knitting course. The class meets 9 a.m. to noon Monday through Friday and ends Jan. 30. It’s part of Carthage College’s J-term — daily courses taught for a few weeks each January between the fall and spring semesters.
Of the 24 students, one is a very strong knitter, about a half-dozen had learned from moms or grandmas and the rest knew nothing about knitting.
So Jensen started by teaching students how to hand-knit — knitting simple things with fingers — to make Celtic knots for potholders. Then students picked up needles and gradually made more difficult items.
On a recent morning, Jensen talked about shapes and how surfaces can look different depending on the viewpoint — like how the Earth seems flat to someone walking along a sidewalk but is actually a sphere when viewed farther away.
“In math, how many shapes are there that look flat but if you zoomed out, it would look different? So we’re knitting something that’s a sphere or a doughnut or a cylinder,” Jensen said.
Students gathered into five teams, with each team given a specific number of colors and a shape to knit: Möbius strip, cylinder, sphere, square and doughnut, known as a torus to mathematicians. Before grabbing rolls of yarn and needles from a large box at the front of the classroom, students sketched out the problem on graph paper.
The team making a Möbius strip with six colors of yarn began by cutting a piece of paper in the desired shape and using markers to figure the color combination. Sam Bednarz, a sophomore from Gurnee, Illinois, and her team members decided to hand-knit strands, rather than using needles, before combining them into a one-sided surface known as a Möbius strip.
Bednarz signed up for the class because she needs a math credit. Plus it sounded fun.
“I thought it was neat to take math concepts and apply them to knitting,” said Bednarz, who admitted some of her friends and family thought she was nuts. “I’ve gotten a few crazy responses. ‘That’s a course?’ ‘This is what we’re spending our money on?’ ” Michael McMurray, a freshman Japanese and English major from Menomonee Falls, wanted a class that’s the equivalent of geometry in 3D.
“I’ve always struggled with math and I wanted a math-friendly course, something that wouldn’t intimidate me,” McMurray said. “This is taking geometry from a school subject into the real world.”
Like many mathematicians, Jensen gets this a lot: When people learn her profession, their first response is usually, “Oh, I hate math.” But when Jensen asks why, they usually say they hate computations and formulas.
Jensen can relate.
“I don’t like computations and formulas either. I don’t think of those as math. Mathematicians will say we’re problem solvers,” said Jensen, a New Berlin native who earned her bachelor’s in math at Carthage. “Much of what I’m trying to get across to my students is that the heart of mathematics is figuring out why something works.”
This is the second time Jensen has taught the class. To create her syllabus, she sought the advice of authors of mathematical crafts books. She uses patterns found online and also devises her own. The last thing she knitted was a purple and white hat with a fall leaf pattern she found online for her 7-yearold daughter, a “Frozen” fan.
Sean Johnson took linear algebra last semester and will study computer science in the spring. But this week the 6foot-10 center for Carthage’s basketball team was busy knitting a square with four colors of yarn.
“I’m a math major so I like math, obviously. I took this class purely for the fun of it and to learn how to knit, to learn a life skill,” said Johnson.
By the end of the class, students have knitted a potholder with a pattern of either a triangle or square, headband, phone case, coffee mug cozy and a baby hat. For their final project, students are free to choose from ideas provided by Jensen or create their own.
Two years ago, in Jensen’s first mathematical knitting class, someone knitted a Rubik’s Cube for their final project.
“And it worked!” Jensen said.