Mitchell Colvin squeezes several drops of green liquid into a vial containing his water sample. He lowers the vial into a plastic box containing several colored, plastic filters then attempts to match the colors.
Behind him, in the Applegate River, dorsal fins on a pair of spawning salmon catch the sunlight for an instant then disappear beneath the water's surface.
"(The) pH is about 7 — good to go for fish; not too acidic, not too basic," says Colvin, a senior at North Valley High School in Merlin.
Colvin and his classmates are spending the day in Cantrall-Buckley Park near Ruch, learning about all things salmon. Approximately 5,000 school children in Oregon each year partake in this one-day outdoor-education class, Salmon Watch, developed in 1993 by the nonprofit group Freshwater Trust (formerly Oregon Trout).
Today's students are led by science teacher Greg Patch, a longtime Salmon Watch devotee.
"The kids here today are not taking science this year. I'm giving them a chance to go into the field," says Patch.
Learning in the field — as opposed to the classroom — is an opportunity Patch values. These types of opportunities are few and far between.
"Many of these kids have never done this, had this chance," Patch says.
The Salmon Watch curriculum is divided into four units: salmon ecology, water quality, macroinvertebrates and riparian ecology. A unit lasts 30 to 40 minutes, then each group of students rotates to the next unit.
In the salmon-ecology unit, a series of bottles serves to teach about a salmon's early life. In the first bottle is a cluster of unhatched eggs. The next bottle holds a group of alevins, each with a yolk sac attached. Each successive bottle shows a further development in the young salmon, ending with a 2-inch fry.
"I learned about salmon eggs. Sand can destroy the eggs even though the water is running. Just a little bit of sand," says Ethan Prow, a North Valley senior.
In addition to the salmon life cycle, students learn about what makes good habitat, the difference between wild and hatchery fish, and how a fish finds its natal stream.
"A salmon doesn't use its eyes to find its way back, it uses taste and smell. The minerals in the water of each stream are different," says Derek Mauldin, Salmon Watch instructor, to the assembled students.
After salmon ecology, students put on waders and walk into the stream. Their task is to turn over cobbles and catch the debris in a kicknet. They hope the debris will catch macroinvertebrates — the bugs that become a salmon's meal.
The bugs are classified according to family. Because of the huge number of macroinvertebrate species, it takes a highly trained scientist to classify one of these bugs to the species — or even genus — level.
Today's find includes mayflies and stoneflies, bugs that are intolerant of pollution. This indicates good water quality, something salmon and students alike can appreciate.
Salmon Watch is taught to children from grades 5 through 12, a challenge that requires constant adjustment on the part of the instructors.
"It lends itself well to different grade levels. The older kids classify bugs with keys. With younger kids, it's just 'look, there are bugs on the bottom of the river,' " says Lauren Kemple, another instructor.
Dissolved oxygen, turbidity and pH are all tested in the water-quality unit. Today, the Applegate River scores an "A" on all counts.
The final unit is riparian ecology. Students look up and around and learn that the large trees on the banks of the river will one day fall over and become places for salmon to hide from predators.
A few trees at this park fell over sooner than expected. What look like hatchet scars on a cottonwood stump turn out to be beaver teeth marks.
It can be a challenge repeating the same curriculum dozens of times in less than two months each fall. What keeps it fresh is the unexpected.
"Last week there was a salmon carcass and the kids wanted to catch it. I kept it in the same pool all week so the kids could see the big teeth, feel the gills, all up close. Of course, each day it smelled worse," says instructor Karen Tassinari.
The unexpected recently took the form of something most people only see in photographs.
"One day an osprey picked up a fish. We've also seen muskrats and mergansers," says instructor Rachel Werling.
When they find themselves near an angler, so much the better.
"Sometimes fly fishermen will stop by and show us their gear. One guy yelled back to shore, explaining to the kids what he was doing," Werling adds.
All four of the instructors work for the Medford-based Jefferson Nature Center, which has partnered with Freshwater Trust to bring Salmon Watch to schools throughout southwest Oregon.
As most high-school teachers know, keeping a kid's attention is a tough job, even in the field.
"I promised them we'd stop at Dairy Queen on the way home if they're good," says Patch. "I remind of that periodically."
Daniel Newberry is a freelance writer living in the Applegate Valley. Reach him at firstname.lastname@example.org.