Yellowdig, a four-year-old, Philadelphia-based education-technology firm whose "online discussion" software is licensed to the University of Pennsylvania, Villanova, and over 40 other universities, has raised another $800,000, lifting its total funding to date to $2.4 million, says Shaunak Roy, founder and chief executive.

The latest funding was led by Musketeer Capital, whose partners include Penn Wharton professor Len Lodish, and was backed by SRI Capital, QBI Ventures, Rosecliff Capital, and angel investor Bob Ciaruffoli, who headed the former Parente Beard when it was the largest Philadelphia accounting firm before its 2014 merger with Chicago-based Baker Tilly.  Earlier funders include 500 Startups, SRI and a group of New York-based funds.

Yellowdig develops a "sense of community in online students" similar to that cultivated by traditional colleges, Lodish said in a statement.

Why not use Facebook Notes, Slack or other communications systems that have grown popular in recent years? Yellowdig posted this note when Facebook disclosed data-security issues earlier this year: Facebook and other mass-market social-media companies typically don't comply with the Family Educational Rights and Privacy Act of 1974, the federal law that prevents sale and sharing of user data — which is how Facebook and other social-media companies stay in business. Social-media platforms collect and sell data on users; Yellowdig and other "ed tech" companies are FERPA-compliant and are required to keep data isolated and secure.

Yellowdig said it offers additional college-friendly services: "anonymous posting options for peer feedback, and conversations on sensitive topics;" a "gamified point system" that gives students incentives to post comment and content, boosting online class participation; and enables posting of computer-science code and math equations.

The system also differs from older FERPA-compliant systems by relying on Amazon Web Services servers — cloud computing designed to speed and secure smartphone communications, making the system easier to use from remote locations.

The firm says its service is available to a total of more than 150,000 students and instructors. Roy called it "a carefully-designed hybrid between a university social network and a course-management tool" that makes it easy to post and discuss syllabus materials and related articles to "dramatically increase overall course participation and management, especially in online or distance programs."

Roy is a former director of corporate business development at FMC Corp., the Philadelphia pesticide and lithium manufacturer.