Henry M., as he’s known in school, slipped his fly into the hook keeper on his new fly rod, stepped from the Rogue River and started walking briskly up the trail.

“I’m glad we’re going back to the car,” Henry said, “because I packed a snack.”

Annnnd…that’s just about what you’d expect from an 11-year-old kid who had just spent two hours of the late afternoon on a school night casting a fly on the water for the first time. Gotta feed the growing beast within.

His younger brother George, he of the understatement, hadn’t waited around for Henry.

“I’m a little wet,” he had said before scurrying up the hill as quickly as he could. As soon as their father helped him strip off the leaking waders and exposed his two wet legs and soaked socks, George let on that for the entire time he had felt water coming in just above where the neoprene divided into two legs. He later told his mother he had been cold the entire time. But because George is a trooper, he had stayed in place in the river practicing and practicing the casting technique Mr. Glen had taught him. He even caught a small brown trout in the process.

“You can tell it is a wild brown,” Mr. Glen advised, “because they don’t plant them this small.”

But the important point to realize is that during his first time ever on a river using his “vintage” fly rod, George had actually caught a trout. Henry caught three, the third one a nice 8-incher he had stalked and hooked on his own: Mr. Glen had been downstream working with George at the time.

With 30-plus years’ experience instructing people of all ages from all over the country, Mr. Glen — Glen Blackwood, owner of the Great Lakes Fly Fishing Company in Rockford, Michigan — knows the ins and outs, the potential and the limitations involved in streamside introductions to fly fishing.

With that in mind, he sets modest goals for that first lesson. He introduces students to some of the natural history involved. For example, he lifted a rock from the river to show the boys its underside and the insects attached.

“I want to get them to develop a straight fly cast and have them swing soft-hackled or wet flies in the current to see if they can take a trout,” he says. “If you can accomplish that, you’re in pretty good standing.”

In tandem, the boys make their first casts.

The funny thing is that there are no secrets or shortcuts: Every thought he offers on the topic is based on simple, common sense.

Showing both cleverness and insight into the educational process, Blackwood introduced many important lessons without identifying them as such.

For example, Mr. Glen had Henry and George string their rods before leaving the vehicles. They tied on no flies, so they had to learn the importance of keeping one’s line snug during the walk to the water, so it doesn’t tumble down through the rod guides.

Upon arrival at the water’s edge, Mr. Glen paused only to mention a couple of things to the boys before leading them into calf-deep water, where he showed them the three-step method of casting: back cast, forward cast, lower rod.

As he explained, the major difference between fly-casting and “conventional” casting is that with the latter method, a plug or lure is the weighted component, and as it heads toward the targeted area on the water, the heavy bait pulls the line from the reel. Fly-casting is just the opposite: The fly weighs next to nothing. The mass needed to power the cast is in the fly line itself, so the cast must be performed in such a manner that the line pulls the fly to the target spot and sets it down gently.

The fly fisherman accomplishes this in three steps: The back cast is the basic foundation of any cast. It uses the rod tip to “cock and load” the fly line with kinetic energy. The forward cast transfers the energy through the line so that it makes a loop that pulls the leader and flies through the air. The third step in the cast is to lower the rod as the line straightens out so the fly will land gently on the water.

So that’s what Mr. Glen wanted the boys to practice. When they did it right, the results were beautiful loops and delicately landing flies. When they lost focus, got tired or forgot step three of the cast, they ended up with a pile of line on the water in front of them. But they persisted, trying to get it right.

Contrary to what one might expect, Blackwood spent zero time having the boys practice their casts on land.

“We could have done that for an hour,” he says, “but they’d get bored. Also, we get them into the water right away, and that helps build the confidence they need, helps them get comfortable casting in flowing water. I don’t tell them that, but it’s what is happening.” He also explains that the physics involved makes water a better surface from which to begin the back cast than dry ground does.

The boys’ father was present, but other than to offer encouragement, he kept his mouth shut and let Mr. Glen do the talking. And according to Blackwood, that’s a good thing.

He gives three reasons for parents to entrust the fly-casting lessons to disinterested professionals. First, “a parent is the parent.” Any constructive criticism or correction one offers can easily be interpreted by kids as personal attacks.

Second, parents often get so focused on what they want their children to learn that they neglect to consider attention spans. And the best way to turn a child off to fishing is to insist he keep at it once his concentration has drifted downstream.

Finally, Blackwood says an instructor is likely to notice some telltales in the kid’s performance — indications of his physical limitations or mental development that prevent him from understanding or performing the nuances of fly-casting. So much of a child’s success is “based on physicality, muscle memory, stature and strength.”

Henry and George experienced success on this trip. And Mr. Glen’s lessons were so subtle they didn’t even realize they had been learning important things.

Back at the car, their discussion centered around…waders!

“At first, when I was wearing them, I was thinking, Hey! I should be getting wet,” Henry smiled.

George joined in, “Being in the waders was kind of weird. I’m used to wearing pants, but not these big baggy things.”

After a minute of sharing their war stories, the boys talked about the fishing itself.

Henry had done some reading on the topic and said, “I thought there would be more back and forth” — false casting — “but there wasn’t.” Nevertheless, “I would definitely do it again!”

George said he appreciated learning where in the water he should cast.

While munching on their granola bars, both boys talked about returning to the river to fish again. When the water is warmer.

“Yeah, and we won’t need to wear waders,” said George.

Then came the sound of children’s laughter.

In the Grand Rapids area, to get fly-casting lessons from Glen Blackwood, contact the Great Lakes Fly Fishing Company (616-866-6060, troutmoor.net).

Blackwood also suggested looking for lessons through local Trout Unlimited (TU) chapters and local sportsman and conservation clubs. He also recommends the Michigan TU Fly Fishing School (tuffs.org) and says the group also sponsors youth fly-fishing workshops (michigantu.org).