This happened just before 10:30 a.m. Thursday.
The school sent out an alert saying that the student was walking on Anita Street near Cullen Street when a man walked up behind the student, pushed him down and stole his backpack.
The robber then climbed into the backseat of a black, four-door sedan that was waiting for him. It left the scene and drove off westbound on Anita Street.
The student received minor scrapes on his arm and hand from the fall.
Police only describe the robber as black male with light skin, between 190-220 pounds. He was wearing a grey or black shirt.
They did not give an age.
If you have any information about the crime, you're urged to call police.