The first-graders of Mrs. Henschen’s class at River Grove elementary school in Marine on St. Croix piled off the bus and sat down on a rock wall next to the parking lot in Interstate Park. This was their third and final river-related activity of the school year, and they brought knowledge and curiosity along with their lunch boxes and water bottles.

They also brought energy. School was almost out for summer.

The year that had started with bringing aquatic insects from the river to the school, followed by a full-day field trip to St. Croix Falls, was coming to an end. Over nine months, the students had worked on reading and writing, music and math, and had become real river kids.

Their feet trod across the St. Croix Dalles’ billion-year-old basalt, the paths worn smooth by generations awe-seekers over thousands of years.

Interstate Park ranger Jenni Webster led the kids on a walk around the park’s famous potholes. The route was short but the time was long. It started with the lava that poured through the Earth’s crust more than 1 billion years ago, through the time of the last glaciers, when rushing meltwater carved the gorge and created the swirling eddies that carved the potholes in the hard rock.

The program was full of movement and questions for the kids, holding their attention and instilling a sense of awe of the beauty and natural forces that created it.

The kids’ questions and shouts echoed off the basalt. They gaped as they looked down into the world’s deepest explored pothole, sixty feet deep.

The most popular attraction was the result of water, winter, and long periods of time. A huge chunk of basalt had been cleaved off a face by water freezing and thawing in cracks in the rock. The rectangular boulder sat a foot away from its source, creating the perfect secret passage for the kids to crawl through over and over.

Next came the hike of just over a mile from the north part of the park to the picnic area at the south end. Jaime Souza of the St. Croix River Association led us up and down along the bluff, taking in the soaring views of the Dalles, waving to people on a paddleboat and a kayaker on the water far below.

In the shady woods, they stopped to identify and admire the abundant wildflowers growing along the trail.

Reaching the south part of the park, where the canoe landing and picnic area is located, we were reunited with our bus, and lunches. Settling in at picnic tables under soaring silver maples, the kids were briefly motionless, devouring sandwiches and fruits and vegetables.

Then they were off again, finally given some free time to play as only a pack of first-graders can after nine months of recess together.

The day was getting warmer, the parent chaperones were starting to slow down, and the children, all sworn Junior Rangers of the National Park Service, were in their element. The river flowed past nearby, birds sang overhead, and we were surrounded by spring’s sublime riches.

Once more, the students were rounded up and introduced to the next activity. It wasn’t much different than a perfect recess: playing in a trickle of a stream that ran through a gully.

Jaime led the group to the sandy stream, and talked about how rivers move, how they react to obstacles, how their eddies can create a current that goes upstream. Then she let them make boats of twigs and leaves and seeds they found on the ground, and spend five minutes sending them down the creek.

The day wound down with a relay race of wondering about natural objects, and a scavenger hunt for a list of items ranging from acorns to litter.

The scavenger hunt seemed to be a perfect ending. The children were exhausted from excitement, so pairing up to range across a small area of the picnic area while looking for small objects on the ground seemed to help them slow down and focus on what was in front of them.

Spring was coming to a close, and summer was only a day away. For these 25 young people, and hundreds more that have taken similar field trips this year, the river in their backyard would be on their mind a lot in the months ahead, and all their lives.

The Rivers Are Alive K-12 environmental education program is a partnership of the St. Croix River Association and St. Croix National Scenic Riverway, a unit of the National Park System.

Learn more and register for a field trip or in-classroom presentation, which are free or low-cost.