Microsoft has acquired education technology startup Flipgrid, Inc., and immediately announced that the subscription social learning platform will be free to all educators.

Flipgrid, based in Minnesota, makes a video discussion tool widely used in classrooms. Teachers can create a visual “grid” for a classroom with one or more topics, and students respond with short videos on browsers, tablets, smartphones, or Chromebooks. The tool is said to be used by more than 20 million educators, students and families across K-12 and higher education in 180 countries. Financial terms of the deal weren’t disclosed.

Microsoft said the startup, founded in 2015, will keep its existing brand and team, even as Microsoft makes a significant change and eliminates paid Flipgrid subscriptions. Those subscriptions ranged in price from $65 per year for an individual educator to $1,000 per year for a school. Microsoft said customers who purchased a subscription will get a prorated refund.

This brings Flipgrid pricing in line with Office 365 Education, which is also free for schools. That’s a key factor as Google’s free G Suite for Education competes strongly with Microsoft in K-12 classrooms. The latest numbers from market research firm Futuresource for Q1 2018 gives Windows OS a leading 44 percent share of mobile computing devices shipping to K-12 schools globally, but Google’s Chrome OS has a dominant 56 percent share of new shipments to U.S. schools in the first quarter.

However, Microsoft said that Flipgrid will continue to support multiple operating systems. “We’re diligently committed to making sure their platform and products continue to work across the Microsoft, Google and partner ecosystems to benefit students and teachers everywhere,” said Eran Megiddo, corporate vice president for Microsoft, in a statement.

We’re diligently committed to making sure their platform and products continue to work across the Microsoft, Google and partner ecosystems to benefit students and teachers everywhere.

Microsoft’s acquisition of Flipgrid comes one week before the major International Society for Technology in Education (ISTE) conference in Chicago, the largest edtech conference and trade show in North America. While a Microsoft spokesperson told GeekWire the acquisition isn’t a key part of Microsoft’s ISTE presence, Flipgrid will present and demo the platform at the Microsoft booth.

The flip from paid to free is likely to come as welcome news to teachers at ISTE. K-12 educators have been stung by startups going the other direction, such as digital bulletin board provider Padlet earlier this year deciding that its generous free level was unsustainable. Amazon’s TenMarks, which had a freemium model, is being quietly shuttered by Amazon without explanation. Flipgrid, too, has had a free offering, a limited “Flipgrid One” level. But now all subscription levels will be free.

Microsoft said there will be new Flipgrid updates announced on August 1 at #FlipgridLIVE, Flipgrid’s annual educator conference in Minneapolis.