The classroom is no place for fighting. Unless it’s between education startups.

In a move that signals an aggressive expansion into the online learning platform market, social learning startup Grockit is hiring Rusty Greiff as chief strategy and development officer. Greiff (pictured) has worked in test-prep and education technology companies for 15 years and had a hand in launching the AmeriCorps program for the Clinton Administration. He also oversaw national educational and technology advocacy campaigns for Senator John Kerry. At Grockit, Greiff will be responsible for strategic growth and large-scale revenue partnerships, including platform licensing agreements, co-branded test prep services and integrated white-label solutions for large education companies.

The hire is the latest move in a what could soon become an education-technology turfwar, in which a handful of online learning companies are beginning to encroach on each others’ territories.

To glimpse the near future of the edtech sector, take a look at the present consumer Internet industry: the Big Boys on the Web — Google, Facebook and Apple — all started out providing completely unrelated services (search, social networking, and computers). Now they’re fiercely competing in the overlapping territories of ad serving and mobile software.

Something similar is happening in edtech. Knewton pioneered the online test-prep platform. Khan Academy is building the world’s education content library. Grockit forged the social learning platform. But all three companies are increasingly competing on content and adaptive learning, and they’ll soon be courting many of the same students and educational organizations as clients. The learning platform sector is on the brink of war.

Grockit CEO Roy Gilbert is keeping his company focused on its main differentiator.

“Our core belief — and this is backed up in educational research — is that one of the best ways to learn new things is to leverage the power of social interactions with peers and experts,” Gilbert says.  “Most technology companies in this space are trying to find ways to serve the best content to a student; we think that the better approach is to create a platform where a community can work together to learn and grow.”

For the time being, Grockit is firmly in control of the social learning territory. Although the non-profit Khan Academy uses some social gaming techniques like points and badges, it doesn’t provide simultaneous drilling and chat the way Grockit does. Knewton has made no move to launch social learning tools. However, test-prep has long been a theater of competition between Knewton and Grockit, and both sides are amassing arms on another front: the white-label learning platform.

Like Grockit, Knewton has hopes of making a broad impact on education by opening up its learning platform to schools, teachers and education companies. Though the two specialize in different aspects — Knewton is purely adaptive learning while Grockit is also a social learning platform — their prospective customers aren’t likely to license both of them.

Gilbert is staying focused on both theaters of the war. He says everything on the current Grockit website and all feature releases planned for this year “serve two business objectives: producing a cutting-edge, rich test prep experience for individual students while simultaneously showcasing a platform that can be used by universities, companies, and more.”

Meanwhile, Gilbert’s new hire has been busy going after customers.

“Rusty has already introduced Grockit to potential partners in mobile consumer services, virtual learning environments like online universities, post-secondary institutions, community colleges, major metropolitan school districts, e-learning companies, work-force training companies, home-schooling and community-based organizations,” Gilbert says.  “Some of these partnerships are already active and will soon be announced.”

To date, the few conferences and mixers in the emerging edtech community have been characterized by the sort of warm, mutually supportive tone typical of the non-profit education sector. That tone could soon take a competitive turn as the rivalries heat up and the race to produce better learning platforms accelerates. This war could be a beautiful thing for students.