MISQUAH — The annual Prairie View Middle School science fair concluded Wednesday with first prize going, for the forty-fifth consecutive year, to a baking-soda volcano.

This year’s winning entry, built by seventh-grader Jaxon Lindholm, stood nearly three feet tall and erupted twice on schedule and once unscheduled, during judging. “He committed to it,” said fair coordinator Lois Hagen, who teaches eighth-grade science. “The paint, the rock work, the little trees. You have to reward commitment.”

Second place went to a project titled “Why Loons Are Heavier Than Other Birds,” a study of bone density by sixth-grader Greta Solberg that several parents described, in the parking lot afterward, as “the one that was actually science.”

The outcome revived a complaint nearly as old as the fair itself — that the judging “rewards spectacle over substance” — a grievance that, by the Pilot-Independent’s reading of its own back issues, has followed all but one of the fair’s forty-five years. The exception was 1981, the last year a volcano did not win; first prize that year went to a model of the solar system, with the volcano placing second amid similar murmuring.

Mrs. Hagen, who has run the fair since 2007, said she was aware of the criticism and unmoved by it. “Every year somebody’s mother tells me the volcano shouldn’t have won,” she said. “And every year the volcano is the thing the kids still remember in twenty years. I’ve made my peace with it.”

The winning volcano erupted a final time at the close of judging. The gymnasium, staff reported, smelled faintly of vinegar through Friday.