By Jill Tucker | SF Chronicle

Math teacher Marcus Hung squinted in mock concentration.

"3.1415," he said before pausing dramatically and then smiling. "That's about it."

Reciting the digits of the irrational number pi is not his specialty. Teaching pi is.

On Friday, his class of high school freshmen and sophomores at San Francisco's June Jordan School for Equity was devoted to pi. And, actually, pie too.

It was officially Pi Day, not coincidentally on March 14 (3/14), a national celebration of the weird, infinite number that allows us to find the area of a circle. But it's also an irrational number, one that goes on and on without repetition of a pattern.

"It plays with your mind," said ninth-grader Eileen Molina, 14.

That, Hung said, is exactly the point of pi and, specifically, Pi Day.

"We're really wanting students to think deeply about what the number implies," he said. "It's a high-level idea."

Freshman Nikki Whittaker, 15, agreed.

"It is a weird, creepy number," she said. "You could start writing it, then have your grandchildren and their grandchildren write it out and they still wouldn't finish."

Yet, undeniably, it's a handy little number, portrayed as the Greek letter pi, a wavy, two-legged table-type symbol.

With a circle laid out in the middle of his classroom floor using colored plastic hoops and straight pieces cutting across the middle, Hung walked the perimeter and then followed the line down the center.

"That," he said, "is pi."

A few students squinted in real concentration and didn't smile.

"We've got this idea that pi is about area," Hung told the students. "I want you to consider that pi can be other things."

And yet, this was Pi Day, which wouldn't really be Pi Day without a contest to see who could recite the most digits of pi.

Hung, clearly not a competitor, kept track of each student's effort. Nikki recited 54 digits, and although she left out one tiny little number 9 toward the end, she still snagged first place. Those who competed were first in line for a piece of pie because it wouldn't really be Pi Day without actual pie.

As students filed out for lunch post-pie, Hung said he generally wants students to have a deep grasp of concepts rather than memorize and recite by rote, but it's also important to make math fun.

"We have holidays celebrating history," Hung said. "Thinking about math as something we can celebrate is really important."

And unlike a lot of other numbers, pi is fun, but it's also really profound, he said.

Then Hung looked down at the empty round pie tins that contained a smattering of pumpkin and key lime pie crumbs.

"These aren't actually pies," he said of the tins, pausing dramatically and then smiling. "Because pi r²."

Damaris Orellana (left, with classmate Jahmal Bolãnos) says she wants to
write out pi instead of recite it.
Photo: Lea Suzuki, The Chronicle |

"3.1415," he said before pausing dramatically and then smiling. "That's about it."

Reciting the digits of the irrational number pi is not his specialty. Teaching pi is.

On Friday, his class of high school freshmen and sophomores at San Francisco's June Jordan School for Equity was devoted to pi. And, actually, pie too.

It was officially Pi Day, not coincidentally on March 14 (3/14), a national celebration of the weird, infinite number that allows us to find the area of a circle. But it's also an irrational number, one that goes on and on without repetition of a pattern.

"It plays with your mind," said ninth-grader Eileen Molina, 14.

That, Hung said, is exactly the point of pi and, specifically, Pi Day.

"We're really wanting students to think deeply about what the number implies," he said. "It's a high-level idea."

Freshman Nikki Whittaker, 15, agreed.

"It is a weird, creepy number," she said. "You could start writing it, then have your grandchildren and their grandchildren write it out and they still wouldn't finish."

Yet, undeniably, it's a handy little number, portrayed as the Greek letter pi, a wavy, two-legged table-type symbol.

With a circle laid out in the middle of his classroom floor using colored plastic hoops and straight pieces cutting across the middle, Hung walked the perimeter and then followed the line down the center.

"That," he said, "is pi."

A few students squinted in real concentration and didn't smile.

"We've got this idea that pi is about area," Hung told the students. "I want you to consider that pi can be other things."

And yet, this was Pi Day, which wouldn't really be Pi Day without a contest to see who could recite the most digits of pi.

Hung, clearly not a competitor, kept track of each student's effort. Nikki recited 54 digits, and although she left out one tiny little number 9 toward the end, she still snagged first place. Those who competed were first in line for a piece of pie because it wouldn't really be Pi Day without actual pie.

As students filed out for lunch post-pie, Hung said he generally wants students to have a deep grasp of concepts rather than memorize and recite by rote, but it's also important to make math fun.

"We have holidays celebrating history," Hung said. "Thinking about math as something we can celebrate is really important."

And unlike a lot of other numbers, pi is fun, but it's also really profound, he said.

Then Hung looked down at the empty round pie tins that contained a smattering of pumpkin and key lime pie crumbs.

"These aren't actually pies," he said of the tins, pausing dramatically and then smiling. "Because pi r²."