Volume 14, Number 5 begins with an interview with Petronela Radu, Olson Professor of Mathematics and Undergraduate Chair at the University of Nebraska-Lincoln. Petronela created a remarkable interdisciplinary course called “Math In The City” where students apply mathematics to solving and understanding real-world problems. In this interview, we discuss Math In The City, Peridynamics, and how she became interested in mathematics.

There are so many ways that math can be applied to gain understanding of real-world problems that Petronela’s course seems like something that could and should be replicated everywhere.

Prof. Radu is our 60th interviewee and there is no doubt that the opportunity to interview all these remarkable women in mathematics has been one of the biggest highlights of Girls’ Angle’s history. It is fortunate that we live in a time where there are several extraordinary women in mathematics. Still, the numbers are far short of what they could be. Among girls, far more mathematical talent is lost than developed.

The cover, *Just a Crumple?*, is, indeed, just a crumpled piece of paper. And yet, Jovana Andrejevic, a graduate student at Harvard’s School of Engineering and Applied Sciences, and her colleagues found order in the seeming disorder of repeatedly crumpled paper. This is a great example that shows how mathematics can spring forth from something that we might not normally pay any attention to at all. In the first half of *Order In Disorder*, Jovana reveals a beautiful pattern in the crease lengths of these crumples.

I learned about Jovana’s work by reading *The Latest Wrinkle in Crumple Theory* in the New York Times. There is always something particularly valuable when we are given the gift of an explanation from the researcher herself because she has first-hand understanding of the material and writes with a telling nuance.

Pamela Harris and Maria Rodriguez Hertz conclude their expository article on the mathematics of juggling, which is also a first-hand account from the researchers, by indicating the connection between Kostant’s partition function and certain types of juggling patterns. Some of the most beautiful theorems in mathematics are about explicit bijections between two, apparently unrelated, sets. That is the subject of this article.

Next, we present this summer’s batch of Summer Fun problem sets. This year, we have contributions from AnaMaria Perez and Josh Josephy-Zack, Laura Pierson, and Fan Wei. AnaMaria, Laura, and Fan have all served as absolutely marvelous mentors at the Girls’ Angle Club. Fan Wei is now a postdoc in the mathematics department at Princeton University. The three problem sets cover Fibonacci partitions, Wythoff’s game, and random variables. Members are welcome to send us their solutions to any of the Summer Fun problems.

We conclude with a brief summary of our end-of-session math collaboration which was created by mentors Vievie Romanelli, Rachel Zheng, and Head Mentor Grace Work. To give members a welcome break from sitting in front of their computers for all these virtual meets, part of this math collaboration sent members rummaging through their homes in search of objects that fit various mathematical prescriptions.

We hope you enjoy it!

Finally, a reminder: when you subscribe to the Girls’ Angle Bulletin, you’re not just getting a subscription to a magazine. You are also gaining access to the Girls’ Angle mentors. We urge all subscribers and members to write us with your math questions or anything else in the Bulletin or having to do with mathematics in general. We will respond. We want you to get active and *do* mathematics. Parts of the Bulletin are written to induce you to wonder and respond with more questions. Don’t let those questions fade away and become forgotten. Send them to us!

Also, the Girls’ Angle Bulletin is a venue for students who wish to showcase their mathematical achievements that go above and beyond the curriculum. If you’re a student and have discovered something nifty in math, considering submitting it to the Bulletin.

We continue to encourage people to subscribe to our print version, so we have removed some content from the electronic version. Subscriptions are a great way to support Girls’ Angle while getting something concrete back in return. We hope you subscribe!