Who is Sagan and for what purpose does Oluo introduce his story?

Sagan was five years old when his mother Natasha got in touch with Oluo. Sagan was being unfairly targeted by his school, his mother believed and when Oluo looked into the situation, she discovered that Sagan’s race was most likely a strong factor in the school’s decision to expel him five months into his kindergarten year. Oluo uses Sagan’s story to demonstrate the ways in which the school-to-prison pipeline has foundations that reach into early childhood and beyond.