CHICAGO (AP) — Maryland students using their shirts to spell a racial slur used against black people at a rally. Pennsylvania students posing with swastika-carved pumpkins. A Montana student photographed with a gun accompanied with a racial epithet.

Racial incidents are appearing to pop up at an alarming rate in the nation's public schools. There were roughly 80 incidents in October alone, by one expert's count, including a Chicago-area student who was charged with a hate crime for racially charged posts on social media.

Many educators note a spike anecdotally, and social media can give such i...