IN MY ninth-grade biology class — the one where we dissected frogs — Mr. Porter pushed us, and we pushed back.

He was a tough but fair teacher who brooked no sophistry, only capricious enough to maintain his authority. Memorable anecdotes livened up the class. I still chew tortilla chips thoroughly because of Mr. Porter's tale of a girl's torn esophagus. And he improved everyone's hygiene the week he related the story of a slovenly cook who gave his whole fraternity food poisoning.

But most exhilarating were the days after tests, when we had the Exam Challenge. He passed out completed tests, reading aloud the correct answers so we could mark them. And we could challenge the questions or answers. If we made cogent arguments that questions or answers were unfair, or ambiguous, and Mr. Porter accepted our argument, then everyone in the class got an extra point on the test.

Two students took the lead in challenging nearly every question and answer. I was one; I believe the other guy is in law school now.

One Exam Challenge day, just after I'd read a book on Clarence Darrow, I tried and tried to no avail. None of my challenges succeeded, probably for good reason. I was distraught. After the challenge, as we sat working at our two-person lab desks, Mr. Porter must have seen my trembling lip.

He walked past my table and, without a word, dropped upon it the bathroom pass, which was his name attached to a human femur.

I took it and went to the restroom and cried, as he knew I needed to. I cried those great gasping teenage sobs and dried my face with rough paper towels. Someone else came in and entered a stall without trying to comfort me. How unusual, after all, is a freshman girl crying in the bathroom at 9 in the morning?

I went back to class still shaken. He had me stay a moment after and said things I don't remember exactly. He probably reassured me that I was smart and driven, that it wasn't all on my shoulders, that it wasn't my job to fight for extra points for everyone.

I don't remember his words. I remember that femur landing softly on my lab table.

We learned the bones of the human body later that year, during the Bone Challenge. Each person in each team had 10 seconds to name as many human bones as possible, while pointing them out on a strung-up model skeleton. The team with the most points got extra credit.

I coached my team members, helping them practice getting the easy ones first, like the rib cage and the skull. All that week I practiced on unsuspecting acquaintances around campus, ignoring their bewildered faces and developing X-ray vision. I honed the order in which I pointed, trying to get all the names out in one huge breath.

I was the last on my team to compete. At Mr. Porter's "Go," I spewed the list, my index finger a pale blur near the white bones. "Skull, maxilla, mandible, clavicle, humerus, ulna, radius, metatarsals, femur ..."

After perhaps 20 bones I heard someone say "Stop."

People eagerly asked Mr. Porter how I'd done. He gruffly said, "Hold on." They had to wait for him to make the tally; I'd gone faster than he could count.

I recall that I did a superlative job and that my team won. But the proudest moment was that pause, that implicit praise, when he acknowledged that I'd gone too fast for him.

As I've grown older I've learned a distaste for scheming over points.

I've learned the phrase "gaming the system," with all its negative connotations. As another teacher pointed out, punning, "True learning is pointless."

My youthful enthusiasm for argument in the cause of free extra credit seems childish and not without a hint of a martyr complex.

Mr. Porter reminded me that excellence was a worthy goal, and that finding loopholes and taking advantage of goodwill wasn't the way to get there.

And chatterbox me looks back in wonder, not just at the lessons but their elegant wordlessness, at the perfect, inevitable sequence of setup and punchline, at the way our bones can be the scaffolding upon which we build our better selves.

Sumana Harihareswara writes for Bay Area Living each week. Please write to her at sumana@crummy.com.