EVERY CALL YOU MAKE: The path to 35 million users begins with a single phone call. First Round Capital, one of over a dozen investors in school communication startup, Remind, explores what the company means when it claims to be “obsessed with teachers.” Among its activities: weekly chats with co-founder Brett Kopf, 90-minute user-testing sessions over Google Hangouts, and teacher “ambassadors” across the country that keep Remind connected with what’s happening in local communities. In fact, the company loves teachers so much that roughly 10 percent of its staff are former teachers.