When Pooja Nath was an undergraduate at the Indian Institute of Technology Kanpur, an elite engineering school in India, she felt isolated. She was one of the few women on campus. While her male classmates collaborated on problem sets, Ms. Nath toiled in the computer lab alone.

“Back then, no one owned a laptop, there was no Internet in the dorm rooms. So everyone in my class would be working in the computer lab together,” she said. “But all the guys would be communicating with each other, getting help so fast, and I would be on the sidelines just watching.”

The experience as a young woman in that culture formed the foundation of her start-up in Silicon Valley, Piazza. Ms. Nath, who was the first woman from her hometown to attend the prestigious engineering school and later escaped an arranged marriage to become an entrepreneur, conceived of the site for homework help in 2009 during her first year at Stanford Graduate School of Business.

Students post questions to their course page, which peers and educators can then respond to. Instructors moderate the discussion, endorse the best responses and track the popularity of questions in real time. Responses are also color-coded, so students can easily identify the instructor’s comments.