Obvious violations of the first amendment in public schools can include a sign with an obvious religious message, a teacher proselytizing, or a school promoted event sponsored by a religious group that includes a sermon or prayer. There are, however, many smaller violations going on all the time that might be harder to see or stop. It takes all of us, checking into our local schools, to police these minor violations and to educate people about the 1st amendment.
Zack Kopplin wrote in ThinkProgress about the efforts of Focus on the Family to infiltrate public schools under the radar: