Boston firefighters cover work shifts for their comrades as a matter of routine, with the expectation they’ll be covered in reciprocation. But a Northeastern University Journalism School investigation discovered that some 70 firefighters owe their colleagues between three months and three years of accumulated shifts, with apparently little administrative oversight.

The faculty/student probe resulted in a story for The Boston Globe, “Trading the call of duty for a call of convenience,” on Jan. 30. It’s just the latest in a long series of investigative stories written under the auspices of professor Walter Robinson’s investigative journalism seminar.

Robinson, a longtime reporter and Pulitzer Prize-winning editor for the Globe before joining Northeastern, said his aim is for “good journalism students to learn to become better reporters by doing actual stories that, hopefully, perform a public service.”

The latest story was produced by two graduate students, Callum Borchers and Cecilia Akuffo and two undergraduates, Gal Tziperman Lotan and Stefaine Geisler, in Robinson’s fall class. The same class, under Robinson’s oversight, produced two page-one stories for the Globe last fall about Suzanne Bump, then a candidate for state auditor, and her apparent violation of property tax law in claiming primary residence in two Massachusetts communities.

“Since spring 2007, when I started, the seminar has produced 19 page-one investigative stories, so we’ve averaged two or three per semester,” Robinson said. “The spring 2011 seminar, which has seven students is doing prospecting on three possible stories.”

“The work professor Robinson and his students are doing puts the School of Journalism in the vanguard of a new trend in journalism, where universities and nonprofits supplement the work of the so-called ‘legacy media,’” said Stephen Burgard, director of the School of Journalism. “This is a wonderful opportunity for our leading students, and it makes a contribution to the future of high-quality journalism at a time when the field itself is in transition because of economic and digital changes. ”

Robinson, himself a 1974 Northeastern graduate, said the class is “a good example of the experiential approach to learning that, I believe, distinguishes Northeastern University and makes its graduates much more attractive to employers.”