Windows 10S promises stronger virus protection and better battery life, and will be available on PCs costing as little as $189 (£146).
Experts said the move was designed to help Microsoft compete better with Google in the global schools market.
The firm said the products would help it reach a greater number of schools.
Microsoft and Apple have long dominated the school computing market, but they have struggled with the recent rise of Google's low-cost Chromebooks, which come loaded with the Chrome operating system and generally cost less than $300 in the US.
According to consulting firm Futuresource, Google devices accounted for 58% of new sales to US schools in 2016 with Windows on 22% and Mac products on