Semiosis Quartet performs from 8 to 10 p.m. Friday at Third Life Studio, 33 Union Square, Somerville. There is a $10 to $15 suggested donation.

Semiosis – made up of violinists Nicole Parks and Kyra Davies, violist Lauren Nelson and cellist Allison Drenkow – continue to highlight work by voices traditionally underrepresented in the new music community. The quartet will perform Curtis K. Hughes’ String Quartet No. 2 (a work Semiosis premiered in 2016); Shih-Hui Chen’s “Variations on the Theme of Plum Blossom”; Jason Huffman’s “Christmas Tree”; and Caroline Shaw’s “Valencia.” Information is here.

Arlington/Cambridge Indoor soapbox rally from 8 a.m. to 5 p.m. Saturday and Sunday at the CambridgeSide mall, 100 CambridgeSide Place, East Cambridge. Free.

A good, old-fashioned Soap Box Indoor Rally – two days of stock, super stock and masters racing, with each day having a double elimination race in the morning and single elimination in the afternoon. Information is here.

Dr. Seuss Birthday Party from 11 a.m. to 2:30 p.m. Saturday at The Harvard Coop, 1400 Massachusetts Ave., Harvard Square. Free.

The children’s author Dr. Seuss’ has a birthday Friday, but the celebration is the next day with story time, play activities and giveaways – first a 12:30 p.m. reading of “Green Eggs and Ham” near the Out of Town News kiosk, then a 1 p.m. free servings of Green Eggs and Ham and birthday cake and a 2 p.m. “Seuss On The Loose” search for 10 Cats in Hats hiding in The Coop. (Pick up clues in the kids’ book department.) Information is here.

Cultural Rhythms Festival 2018 with Solange Knowles from 4:30 to 6:30 p.m. Saturday at Sanders Theatre, 45 Quincy St., near Harvard Square. Tickets are $20.

This Harvard cultural festival selects a distinguished artist to be honored as artist of the year – and Solange takes the honors for 2018, with tickets still in limited availability. Information is here. (It might be worth knowing that party rock icon Andrew W.K. will be also be in Harvard Square – for a 1 to 4 p.m. Saturday signing at the Newbury Comics in The Garage mall. Wristbands are free with purchase of his new album “You’re Not Alone,” out Friday.)

Ladies Rock Camp 2018 March Showcase from 8 p.m. to midnight Sunday at Once Lounge + Ballroom, 156 Highland Ave., Somerville. Tickets are $15 in advance, or $17 at the door.

Nine brand-new bands take the stage in this eighth year of showcasing the work of the nonprofit Girls Rock Campaign Boston. The girls gather in Jamaica Plain to form bands and create music, part of a program encouraging the people of Greater Boston to sing out and speak up. Information is here.