Blackman was disappointed that he was alone, standing outside his school for 17 minutes. He posted a video on Twitter showing that no one else walked out with him.
The 16-year-old returned to class, and while he was hoping not to get in trouble with school officials, he actually received accolades for standing up for something he believed in, CNN reported.
And while he was alone in the school’s parking lot, he was not alone on social media where supporters sent him messages supporting his decision to walk out.
There were other students who were the the lone walkouts at other schools in the nation.
Leonardo Aguilar is only in second grade, and his class didn't participate as a group, but he joined students who are much older than him at a nearby high school in San Jose, California, to lend his small voice in a big way, KPIX reported.
It was the same for Rosa Rodriguez. She was also the only student to walk out of her New Jersey high school. But her reason for being alone was different than the others. WABC reported that her principal threatened students with discipline if they walked out of the building. They were allowed to go to the gym to remember the Parkland victims, but Rodriguez still walked outside despite the threat of suspension.