McGraw-Hill Education today announced a deal to acquire a 20 percent equity stake in Area9 Aps, the Denmark-based adaptive learning company.

The move strengthens McGraw-Hill Education's positionas the leader in personalized learning through adaptive technology.

Terms of theinvestment were not disclosed.

McGraw-Hill Education's equity investment in Area9 marks the culmination of a longstanding relationship between the two companies.

Since 2007, McGraw-Hill Education and Area9 have worked together to develop products that deliver personalized learning experiences by using adaptive technology to continually assess students' knowledge and skill levels and design study paths that bolster students' understanding in the areas where they need to improve the most.

By allowing students to focus their outside-of-class study time on the topics and concepts that are most challenging to them, McGraw-Hill Education's adaptive solutions have been shown to help students study more efficiently, develop greater proficiency and earn better grades.

As part of the agreement, McGraw-Hill Education and Area9 will work together to develop new adaptive learning products, both within and outside the higher education market.

The result of the companies' first collaboration, McGraw-Hill LearnSmart, immediately became the leading adaptive study tool in higher education upon its release in 2009. Recently, the number of products built on the LearnSmart technology has expanded: At the recent Consumer Electronics Show in Las Vegas, McGraw-Hill Education announced the launch of the LearnSmart Advantage suite of adaptive learning products, which it developed in conjunction with Area9. The LearnSmart Advantage suite includes SmartBook, the world's first-ever adaptive e-book.

"At McGraw-Hill Education, we have a passion for teaching and learning, and we believe that delivering personalized experiences through adaptive technology is a key ingredient to teaching and learning success," said Brian Kibby, president of McGraw-Hill Higher Education. "Through our investment in Area9, we're working to create more deeply integrated teaching and learning experiences that we see as a central element in the future of education."