On a rainy afternoon in Abbeville, La., hundreds of people showed up on Thursday to a rally in support of Deyshia Hargrave, a teacher whose arrest at a school board meeting ignited a national backlash.

Many of them heeded calls to wear black in support. Speakers said her experience at the meeting on Monday was a clear illustration of educators struggling to make their voices heard.

Ms. Hargrave, who took the microphone to chants of “Stand by Deyshia,” said she hoped she would inspire people to show up to their local meetings, and her students to stand up for what they think is right.

“I want them to see past the handcuffs and the arrest, and I want change to come from this,” she said.