Today in Tech: Your e-textbooks are watching you by JP Mangalindan @FortuneMagazine April 10, 2013, 7:20 AM EST E-mail Tweet Facebook Google Plus Linkedin Share icons Also: Pandora reports some stellar user numbers; why Marissa Mayer really paid $30 million for a startup. Teacher knows if you’ve done the e-reading [THE NEW YORK TIMES] They know when students are skipping pages, failing to highlight significant passages, not bothering to take notes — or simply not opening the book at all. “It’s Big Brother, sort of, but with a good intent,” said Tracy Hurley, the dean of the school of business. Microsoft escalates ad assault on Google [AP] This time, Microsoft is vilifying Google Inc. for sharing some of the personal information that it gathers about people who buy applications designed to run on smartphones and tablet computers powered by Google’s Android software. Earlier ads have skewered Google’s long-running practice of electronically scanning the contents of people’s Gmail accounts to help sell ads and attacked a recently introduced policy that requires retailers to pay to appear in the shopping section of Google’s dominant search engine. Pandora surpasses 200 million registered users, 140 million access via mobile [TECHCRUNCH] Growth in registered users is surely something to be excited about, but what’s most important to a service like Pandora is monthly active users. At the end of March, Pandora boasted 69.5 million monthly active users, which is up from 59.9 million in December of 2012. In fact, the company has shown steady growth in MAU over the past couple years. Why Marissa Mayer bought a $30 million startup [BUSINESS INSIDER] A source close to Yahoo says that CEO Marissa Mayer believes summarization technology is “going to be huge for Yahoo” as it builds “personalized news feeds” into mobile versions of its “core experiences,” including Yahoo Finance and Yahoo Sports. Don’t miss the latest tech news. Sign up now to get Today in Tech emailed every morning.