Capella Education Company has acquired the remaining stake in Sophia Learning, LLC-a technology start-up that operates a teaching and learning website that weds education and social media and is billed as “first of its kind.”

Minneapolis-based Sophia is now a wholly owned subsidiary of Minneapolis-based Capella, which has been a majority investor since January 2011. Capella bought the remaining stake from Minneapolis-based digital ad agency GoKart Labs, which developed Sophia with seed funding from Capella. Sophia was spun off from GoKart when Capella provided a round of funding in 2010.

Terms of the transaction weren't disclosed.

Sophia is a teaching and learning website that allows anyone to upload tutorials on topics such as math, English, or science for free. These tutorials, or “learning packets,” can also be viewed for free by anyone, anywhere.

Sophia allows instructors at schools and colleges to create groups that let them share their class content privately-and it offers students multiple tutorials on various topics that provide many different ways for them to learn a particular concept.

A public beta version of Sophia launched in March 2011, and the website is now used by individuals from more than 170 countries who collectively represent 5,000 schools and universities.

“Thanks to Capella's support, by month's end, Sophia will offer nearly 30,000 academic tutorials and quizzes-all free-and comprehensively cover . . . 14 different academic topics and counting-including algebra, geometry, physics, chemistry, and English,” Sophia founder and former CEO Don Smithmier said in a Monday e-mail announcement sent to his family, friends, and colleagues. (Smithmier also cofounded GoKart.)

Steve Anastasi, who used to be Sophia's chief technology officer, recently became CEO. Capella said that Smithmier will continue in an advisory role while Anastasi assumes executive responsibilities.

“Over the last year, we have watched Sophia evolve from a promising start-up to a leader in social education and a valued resource for students and teachers,” Capella Chairman and CEO J. Kevin Gilligan said in a statement. “This investment is part of our long-term strategy for Capella. It aligns with Capella's mission of extending access to education on a broad scale, puts critical tools in the hands of our learners and faculty to improve learning outcomes, and provides an innovative pathway to lower the cost of higher education. Additionally, Sophia provides us with a sandbox for innovation and experimentation in the key areas of social teaching and learning, assessment, and adaptive learning.”

According to Smithmier, some interesting things are on the horizon for Sophia. Without providing many details, he said in his letter that it will take aim at “one of the most important issues facing American education: the cost of college tuition.”

He added: “In the weeks and months ahead, you'll be hearing more about Sophia/Capella programs that will allow students to earn college credit at a fraction of traditional costs.”

A Capella spokeswoman confirmed Tuesday that Sophia, which has 14 employees and 25 contractors,  isn't yet profitable.