In the first-floor classroom of Boulder Lake Environmental Learning Center north of Duluth, a group of about a dozen people turn to face the front of the room. A cedar strip canoe hangs from the ceiling. A child's orange life jacket is draped over a chair. Magnifying glasses, siphoning tubes, samples of bark and pine cones, stones, and a rodent jaw line the tables in the back. The room smells like a terrarium—wood shavings, moss, rubber boots.

At the front of the room stands phenologist, teacher, author, and spider expert Larry Weber. He flips the lights off, and for a moment the room is dark. Then the overhead projector clicks on, dimly lighting the space again.

"Here it is, folks, one of the greatest photos taken in the history of the world," announces Weber. Several people chuckle as a spider appears on the screen stationed at the hub of a circular web. Weber continues.

"What do we notice first about this photograph?" Several hands go up.

"OK, first of all," he says, "we notice that the spider is upside down."

Even published photos sometimes get this wrong, Weber explains, but this particular species, the yellow garden spider (Argiope aurantia), typically faces down in order to hunt.

"Always?" someone asks.

"Great question. When you study nature you always avoid always and you never say never. Remember, Mother Nature doesn't count." The saying is Weber's reminder to allow for the unexpected in nature. A flower that is shown to have five petals in a field guide, he says, may sometimes have four or six.

On this brisk morning in early May, Weber is teaching these Master Naturalists about spiders of the north woods. Minnesota Master Naturalist is a University of Minnesota Extension program that trains citizen naturalists to serve as environmental stewards across the state. Master Naturalists participate in service projects, attend trainings, and volunteer to teach—providing the public with accessible, current information on conservation issues close to home. Trainings are led by veteran naturalists like Weber, who work throughout the state at nature centers, in schools, or in the woods surrounding their homes.

Weber is in his early 70s with a curly gray beard and bushy eyebrows. The round features of his face exhibit the buoyant cheer and enthusiasm that he brings to his teaching. Today he wears a simple tan baseball cap—a memento from a recent birding trip to the Ozarks. The brim shades his small eyes, which appear to be permanently squinting.

Weber's work bringing science to the public has taken many forms. Now retired, Weber taught middle and high school biology for about 40 years and continues to teach in various capacities—through public speaking, naturalist trainings, books of nature writing, and a weekly nature column in the Duluth News Tribune.

In his teaching, Weber is deliberate, self-deprecating, and precise. He has found his calling in education and a suitable challenge in his subjects—both students and spiders. Spiders are his passion, and they are as ubiquitous in his teaching as they are in our woods and homes. Weber's Spiders of the North Woods, now in its second edition, was the first comprehensive field guide to local spiders. As to why he is drawn to these animals in particular—well, pick up his Web Watching: A Guide to Webs and the Spiders That Make Them, which won a national book award in April. The book takes a unique approach to spider identification by using webs as a starting point for identifying the engineer—similar to the way we might identify a bird from its call.

Weber has a rare combination of deep knowledge, passion for the environment, and zeal for teaching, says John Geissler, a longtime colleague and friend of Weber and the former director of Boulder Lake ELC.

"Larry will take something he has seen hundreds of times," Geissler says, "and make it as if the first time."

Weber grew up in a large family on a small farm in northwestern Ohio, where he began "critter watching" as a child in the 1950s while walking the woods near his home—a concept that would later become foundational to his teaching. Citing a continuity of purpose and passion from an early age, he often puts it this way: "When I was about 8 years old, I went for a walk, and I'm still taking that walk now!"

An early interest in biology and teaching led him to a bachelor's degree from Christian Brothers University in Memphis,Tennessee, and then a master's from St. Mary's University of Minnesota in Winona—his introduction to the state. He taught for several years in St. Louis before moving to Minnesota in the late 1970s, where he taught tenth- and then seventh-grade biology at Duluth's private Marshall School. He often refers to seventh-graders as "the greatest people in the history of the world."

Weber is amicable, warm, and relentless in his work to raise awareness and to foster enjoyment of the natural world. Rain and shine are on even footing for Weber, who is adamant that the experience of crummy weather is a false perception based on crummy preparation. This philosophy has certainly aided his study of phenology, which tracks nature's changes from the first indicators of the season, such as the return of spring warblers, to broader weather patterns, moon phases, and astronomical events shaping the natural world. It was a discipline popularized in the late 1800s by American naturalists such as John Muir and John Burroughs, who studied nature and the seasons directly as a science, in place of textbooks and other traditional Western means of education.

An accomplished phenologist is a scientist who has developed a deep understanding of nature's cycles by meticulous recordkeeping and observation. A famous phenologist once claimed that if he were to wake up delirious in a swamp, he could guess the date of the year within two days by the information of his surroundings.

Weber broadcasts his encyclopedic knowledge of the natural world each Friday on KUMD Duluth in a phenological report of northeastern Minnesota called, like one of his books, Backyard Almanac. He typically reports in the sustained manner of a filibuster, recounting every natural wonder and statistic from the week in one long phrase, hyphenated by short breaths. A September broadcast titled "Why Did the Snapping Turtle Cross the Road?" goes on for more than nine breathless minutes as we follow him from one end of the daily rainbow to the other: yellow birch; red maple, dogwood, sumac; active chipmunks; saw-whet owls.

Every day for more than 34 years, Weber has recorded his observations in the woods near his home, an old farm in Carlton County that he has named WebWood. No longer a working farm, WebWood has been left to grow wild with minimal human intervention. In one journal he notes all that he saw that day, including the first sightings of birds, reptiles, amphibians, butterflies, dragonflies, spiders, wildflowers, and tree flowers. He also records dates of thawing and freezing, high and low temperatures, winds, precipitation, moon phases, and other statistical data. In a second journal, he selects one phenomenon of the day to explore in greater depth in the form of a short essay—a practice that allows him to feel good about each day.

While climate change and other sobering news dominates the headlines, Weber says that phenology offers us another kind of daily news. "Each day I take a few walks, and each day I find a new story to be seen and observed," he says. "The changing seasons provide a backdrop, and no matter the weather conditions, nature is always happening."

Led by Weber, the Master Naturalists have left the classroom for a field trip in the airy hardwood forest of Jay Cooke State Park, amid a light rain and the smell of damp leaves. The glow of Lake Superior projects a silver cast on the cloudy sky. As the group gathers for a brief talk on the state of the woods, a small brown spider idles in the air near Weber's clavicle, dangling on a silken dragline. Several participants point their binoculars and find an audience of eyes on the other end. Weber extends his hand, and the arachnid, a crab spider (Xysticus sp.), steps onto it, settling lightly before dropping from his palm into open air. He calls this "spider yo-yo."

As the spider descends a new dragline toward the matted ground, Weber raises his arm up high to show us its work. The spider pauses, needling the air with its legs, then reverses course, gathering its silk as it climbs. With his free hand, Weber cuts the air to show us that there is no silk underneath—web builders like this one will consume and recycle approximately 70 percent of their silk for the construction of new webs. "I used to tell the kids, it's like climbing a rope in gym class, pulling the rope up behind you," Weber says, "and then eating the rope."

As the class fans out over the forest floor, the woods come alive with spring beauties, bellwort, wood anemone, nodding trillium, and other ephemerals, short-lived wildflowers that bloom in the spring before the leaves have fully emerged on the trees, when the sunlight is still able to reach the forest floor. As the leaves of the upper canopy emerge, the ephemerals fade, and the understory of other ground cover and shrubs emerge in their place. By Weber's measure the spring will be over when the flowers appearing in the sunny meadows and fields outside the forest outnumber those within, but there are many flowers here yet.

After a brief lunch, the class returns to Boulder Lake for a late afternoon lesson on ticks taught by a different instructor. Slipping off his shoes, Weber props open the classroom door with one of them. A wedge of yellow sunlight warms the carpet as the afternoon air rushes in. Drawings suspended on a string flutter on the back wall. As soon as it begins, the lesson is interrupted by the metallic and prescient call of spring warblers from outside. "Terrific, terrific," says Weber, who is fond of the phrase, "If you can't do one thing in nature, do something else."

He grabs his binoculars as the class moves outside to a pine tree. More participants emerge from the classroom, smiling and pointing as the birds move along.

"Wow, yes! Great discovery!" Weber praises the birders, but his attention shifts. Someone has spotted a spider under the picnic table. Weber sharpens his focus as a crowd gathers around the table, and someone hands him the spider, a furrow orbweaver (Larinioides cornutus), in a petri dish. A chorus of spring frogs quack, snore, and jingle nearby.

"Now, as you'll see …" he begins, lifting the lid with care, but before he can finish his thought, the spider steps out of the dish and disappears through a crack in the picnic table. The crowd jeers, but Weber's steady enthusiasm tips the mood.

"Well, who can I blame?" he concedes, stooping down as the newest class of Master Naturalists laugh and join him under the picnic table.