Innovations of Cambridge Tour from noon to 1:30 p.m. Saturday and Sunday. Admission is $15 for adults, $12 for students and seniors, $7 for kids ages 9 to 13, and free for kids 8 and younger.

Harvard Square is great and all, but Cambridge has too much history as a home for innovation to let all the tourist love stay stuck down Massachusetts Avenue. Now there are Cambridge Historical Tours guides (wearing lab coats) who will share some of that innovation history with locals and tourists in a walking tour that shows off not just the birthplaces of such advances as “Guitar Hero” and the biomechatronic foot, but the locales of infamous hacks by MIT students. Information is here.

OpenAir Circus at 2 and 7 p.m. Saturday and 2 p.m. Sunday at Somerville’s Conway Park, on Somerville Avenue at Central Street. Suggested donation of $3.

The OpenAir Circus, a nonprofit, community-based program, is ready for its annual showing off of skills its students learned during summer classes. This 29th annual show features around 170 children as well as adult performers in “A Haunted Circus.” The show is about two hours long with one 15-minute intermission, and refreshments, souvenirs and circus equipment will be available. Information is here.

Boston Roller Derby’s Cosmonaughties vs. Arkham Horrors at 6 p.m. Saturday at Simoni Ice Rink, 155 Gore St., East Cambridge. Tickets are $14 for adults (winding up as $15.48 with the service fee) or $12 for students with valid ID (which is $13.41 with the service fee) or $5 for kids age 6 to 17 (meaning $6.17 with the service fee) and free for kids under 6 (still free with the service fee!).

Tickets include admission to the Arkham Horrors’ debut Cambridge matchup and an after party with the Boston Derby Dames at the Massasoit Elks Lodge, 55 Bishop Allen Drive, Central Square. Information is here.

“Copenhagen” presented by the MIT Shakespeare Ensemble from 8 to 10 p.m. Saturday at the Massachusetts Institute of Technology’s Kresge Little Theater in Kresge Auditorium, 48 Massachusetts Ave. Free.

Is there a better play for an MIT troupe to take on? “Copenhagen,” by Michael Frayn, explores the parallels between uncertainty in physics, history and memory as two giants in the field of physics, Niels Bohr and Werner Heisenberg, reflect from beyond the grave on a 1941 meeting that changed the course of human history – but with different memories  of the meeting. What actually happened remains ambiguous, as do their true motivations and character. The play probes questions about science and morality, how the quest for knowledge is affected by political climate and the uncertainty that exists in all of our interactions with each other and the world. Information is here.

Ed Schrader’s Music Beat and other bands at 10 p.m. Saturday at Lilypad, 353 Cambridge St., Inman Square. Tickets are $5 to $10 on a sliding scale.

Boston Hassle presents an all-ages show that gives you a choice of hometown and what grade of low-fi rock duos you most want to hear. (Hint: All three!)

Allston is represented by (Los Greys), founded by Future Days’ N. Rocco. The band unfortunately shares a name with a Latin pop group, but can’t be mistaken for that band’s sentimental Norteño sound: In (Los Greys)’ manipulation of electronics and samples there’s a touch of nightmare, whether it’s a base of Asian strings sounded murkily, like through water, or innocent retro sounds darkened with hints of mystery and danger.

Here’s (Los Greys) on an extended, murmuring jam at a Savage Weekend gathering in North Carolina:

Ed Schrader’s Music Beat, visiting from Baltimore, has a delightfully nasty sound – the product of writer and comedian Ed Schrader, who plays drums, and bass guitarist Devin Rice. The band specializes in short songs (about two and a half minutes is common) and some fairly sophisticated videos that are surprisingly funny in support of songs that tend toward the ominous. If you don’t understand how creepy it can be to hear Ed Schrader say “I can’t stop eating sugar” over and over, well, you haven’t heard Ed Schrader’s Music Beat playing “I Can’t Stop Eating Sugar.” For a sense of how the band does it live (which is fast and intense) this is the video to check out, but for a sense of the band’s playful range, try “Laughing”:

Chain & the Gang, from Washington, D.C., is certainly the most storied of the bands playing. It’s the latest outlet for Ian Svenonius, the sardonic writer and talk show host who made a name for himself in the late ’80s and early ’90s with the punk band Nation of Ulysses and its follow-ups. The music may have changed a bit, but Svenonius hasn’t, and you can expect a lot of sneering takes on U.S. culture that insinuate themselves through deceptively simple and even occasionally sweet tunes – and even more of the meta commentary Svenonius is semi-famous for, in which he comments on his own music as he plays it and rock lifestyle as he lives it. Hence the ironic manifesto of “Minimum Rock N Roll”:

And the genial satirical idiocy of “Devitalize”:

Information on the show is here.