In time for the back-to-school season, Google (s GOOG) will start selling and renting digital textbooks through the Play store in August, the company announced at a breakfast in San Francisco this morning.

The main point of the breakfast was two bigger announcements: The Chromecast, a $35 dongle that lets you stream internet video to your TV, and a new Nexus 7 tablet. Nonetheless, getting into the textbook market helps Google compete against Amazon (s AMZN), Barnes & Noble (s BKS) and Apple (s AAPL), all of whom have already entered the digital textbook space. In general, Google has struggled to gain ebook market share against those companies.

Google says it’s working with the five largest textbook publishers — Cengage, Wiley, Pearson, McGraw-Hill and Macmillan — and that students will be able to purchase digital textbooks or rent them for up to six months. It also said that prices…