Students at Martin Luther King Jr. High School left at noon on Friday to demonstrate against the district's plan to turn it into a charter school.
The Philadelphia Inquirer reports Audenried High School students left class earlier this week and West Philadelphia High School students walked out on Feb. 11.
King and Audenried will become charter schools under the plan to improve the lowest performing buildings. West Philadelphia will be restructured.
Schools spokeswoman Shana Kemp said in a statement Friday that while students have the right to express their opinions, the district "will hold students accountable for their misconduct."