If you’re looking to expand your knowledge of Chicago hip-hop history I’d suggest heading to Subterranean on Saturday for a Chi-Rock Nation blowout. The show is presented as part of the organization’s 30th anniversary, though that big commemoration is a little premature. That’s because the Chi-Rock Nation officially formed in 1985 with the desire to celebrate the four original elements of hip-hop (breaking, MCing, DJing, and the gerundless act of creating graffiti). Like the Zulu Nation, the influential international hip-hop organization Afrika Bambaataa founded in the 70s, there’s a streak of positivity that drives Chi-Rock, and Saturday’s show is a testament to that element—it’s a fund-raiser for the organization’s third annual Back to School Jam, a free hip-hop event where Chi-Rock devotees pass out school supplies and food to families at Clarendon Park.

Everyone slated to play the Subterranean show is a member of Chi-Rock Nation, and they’re all performing for free so the proceeds can go straight to the back-to-school bash. Nearly two dozen acts will appear onstage, including Ang 13—she contributed a track to the out-of-print 1995 Talent Fest compilation the Reader streamed a couple months ago, and she’s readying a collaborative album with Longshot under the name Army of Two. Take a listen to Army of Two’s “Crank It” below and prepare for Saturday’s show. Also be sure to leave Sat 8/2 open in your calendar—that’s the day Chi-Rock Nation throws its Back to School Jam.

Leor Galil writes about hip-hop every Wednesday.