In a big leap into a new but adjacent market, Silicon Valley digital education start-up Kno said it is entering the K-12 space, expanding from its college-only focus, All Things D reports. Its first step will be a partnership with major textbook publisher Houghton Mifflin Harcourt, which provides nearly half of such content aimed at children from kindergarten through high school. Enhanced digital versions of those textbooks cost $9.99 or less — Kno gets a piece of each sale — and can be used via an Apple iPad app and also on the Web. Kno said its platform will also be available soon on Google Android and Microsoft Windows 7. I did a video interview today with Kno co-founder and CEO Osman Rashid at the global HQ of All Things Digital about the effort, which is a big jump for the company that started off trying to make its own tablet device. Armed with a pile of venture funding, it has pivoted drastically — Apple and then Google completely blew its stillborn hardware efforts up [1] — into creating an educational software platform…