With fall in the air, I get this funny feeling that my homework isn't done.

It is true I was one of "those" students who tested patience, strained policies, broke rules and spent quality time on a chair in the hallway. I guess it was a natural aptitude, like yodeling. My parents urged me to reach my full potential, but how could I do that when it took so much effort just to stay out of the principal's office?

Despite my shenanigans, there were a few dedicated teachers who left an indelible mark. One such teaching champion was Mr. Richard -- or so we called him -- who taught biology at University High School in Greeley, Colo.

Mr. Richard was probably crazy. He willingly took a hormone-imbalanced sophomore class to Colorado's North Park, where we camped for a week in an 8,800 foot-high mountain valley. Born and raised there, he knew it cold, lecturing to us about everything from wildlife to native plants, while most of us guys drooled at girls who hadn't bathed in three days. Oh, to be young again.

Besides field trips, Mr. Richard organized school-wide recycling efforts and conducted roadside cleanups. He brainwashed me so well that even in the dead of winter I can't stop myself from getting on a mountain bike for my three-mile commute to work.

Sure, we endured detailed lectures about human development and the lifecycle of minute organisms. Maybe there were not as many reproduction details as a group of adolescent guys wanted, but from a clinical standpoint, we learned all that was necessary. Best of all, there were Petri dishes, wax dissection trays and powerful microscopes -- all sources of great adventure.

But it was the outdoor activities that made biology a blast.  We'd get on a bus and head to what seemed like remote destinations. Once it was a trip to collect water samples downstream of the newly built and highly controversial Fort St. Vrain nuclear power plant, north of Denver. Another time, with nets in hand and making clucking noises, we hunted down elusive "snipes" in the tall grass prairie northeast of Ault, Colo. This was possibly Mr. Richard's idea of revenge.

Mr. Richard cared about that buzzword "sustainability" early. One field trip to the bluffs of eastern Colorado, just past Grover, population 153, on a good day, we found ourselves at an original pioneer homestead. It boasted no indoor plumbing, no electricity, and a second-generation settler who had no recollection of ever needing such contrivances. Mr. Richard's lesson: Today's luxuries aren't really necessities.

These days, strange terms like photosynthesis, protoplasm, osmosis, and zygote pop into my aging and not always responsive brain. I have a vague notion what they mean, would have typed "fotosinthesis" without spell check, and most certainly acknowledge they are essential elements of the biological world. Yet it wasn't memorizing those terms that Mr. Richard saw as important, because he knew that while not all students became biologists, they all became earth-impacting adults.

Mr. Richard tried to pound into us his conviction that all life forms were essential. I still have doubts about killing a spider crawling across the bedroom ceiling (my wife, on the other hand, does not.)  Thinking back, I realize that his class lectures weren't all that fascinating -- heck, we were out-of-control high schoolers. No, what proved to be the deal clincher was Mr. Richard's passion for what he taught.  Maybe passion isn't the right word. It was more an obsession that "everyone needs to understand the importance of the living world around them."

Sometimes, Mr. Richard seemed as loony as a near-sighted amoeba. It took us a while to understand that he hailed from that class of excellent teachers who continue to influence our lives long after we leave their classrooms.

So, as you teachers prepare your classes, remember that your lessons today aren't just a discussion on some esoteric topic like the heterothermic mammal's circulatory system. What will stick in your students' minds long after they leave will be your enthusiasm, your dedication, your passion for teaching. Of all the professions in the world, none can offer that kind of privilege or challenge. And should you see my old biology teacher out there, tell him he was the greatest!  Also mention I wasn't the one who put the snakes in the sleeping bags.

Joe Barnhart is a contributor to Writers on the Range, a service of High Country News (hcn.org). He pedals to work in Dillon, Montana.