## Girls’ Angle Bulletin, Volume 12, Number 5

This issue’s interview subject is Tanya Leise, Professor in the Mathematics and Statistics Department of Amherst College.  Tanya uses math to study circadian rhythms. She also has a mathematically gifted daughter and in this interview, we ask her about best practices for raising a mathematically gifted child. One of the tools in Tanya’s mathematical toolkit is the wavelet. To enable readers to get an even better idea of what a wavelet is, she also contributed the first Summer Fun problem set in this summer’s batch of Summer Fun problem sets.

Next, four students explain some of their discoveries about what happens when you fold a rectangular strip of paper in half, over and over. You’ll create a model with several layers. Exactly how are these layers ordered? They give a comprehensive answer. Their work inspired this issue’s cover, which represents a rectangular stripped folded in half 6 times to create 64 layers. (By the way, it’s a myth that you can’t fold a paper in half more than a certain number of times. It depends on the thickness and length of the paper.)

Deanna Needell delves deeper into graph theory with her 8th installment of The Needell In The Haystack where she defines the chromatic number of a graph and establishes some basic bounds on its size.

In addition to Tanya’s Summer Fun problem set, Whitney Souery, Laura Pierson, and Matthew de Courcy-Ireland return to give us two more, one on sine and cosine and one on ordinals. Whitney’s Sine and Cosine is designed for anyone who has not yet learned about the sine and cosine function but would be interested in challenging themselves to learn about them by solving problems. Laura and Matthew introduce ordinals, then provide a series of problems that recover work of Paul Erdős in How High Can You Count?

We conclude with brief notes from the club.

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!

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!