https://www.edx.org/school/high-school-initiative

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Colleges and universities find that many students could benefit from taking a few extra courses to help close the readiness gap between high school and college. To address this need, edX has launched a high school initiative--an initial collection of 27 new online courses, including Advanced Placement® (AP®) courses and high school level courses in a wide variety of subject areas.

A generous grant from the Laura and John Arnold Foundation, along with grants from the Wertheimer Fund and Fariborz Maseeh / The Massiah Foundation, will help fund edX’s high school initiative. All 26 courses will be offered for free with some courses offering a Verified Certificate of Achievement option, available for a fee that varies by course.

These courses will better prepare high school students for college and offer learners of all ages an introduction to new areas of study and disciplines. Students can use the courses to prepare for college and the AP exams and to supplement AP coursework. Teachers can also use the new high school course materials to augment their classroom curriculum.
Discussed by a blogger at http://gasstationwithoutpumps.wordpress.com/2014/09/10/edx-finally-finds-the-right-market/ .