Social-networking upstart Teachbook said Wednesday it would challenge a trademark infringement lawsuit brought by Facebook, which is demanding the teacher-oriented site remove “book” from its name. “It’s a David and Goliath situation,” said Greg Shrader, the managing partner of the Northbrook, Illinois-base Teachbook, which has yet to launch.  ”They’re throwing bombs at a mosquito. They believe we’re going to roll over and in some respect they get to own the term ‘book.’” Facebook, in a lawsuit Threat Level reported on Tuesday, claims the term “book” cannot be used to name social-networking sites. The Palo Alto-based site claims Teachbook might dilute its famous ...