It seems that recent years have seen an uptick in the attention being paid to recreational mathematics. The death and centennial of the birth of Martin Gardner probably play a role in this, especially with the biennial Gathering For Gardner conferences and annual Celebrations of Mind held in his honor. The opening of the Museum of Mathematics in New York City has helped increase the visibility of the discipline, as has the proliferation of people who write blogs or books designed to popularize mathematics. In addition to the other activities in this increasingly crowded area, recent years have brought a biennial Colloquium in Recreational Mathematics held in Portugal. The conferences are sponsored by the Ludus Association, who have also recently started publishing the semi-annual Recreational Mathematics Magazine, and some of the papers from the third such conference, which was held in April 2013 at the University of Azores, have been collected in a Proceedings volume.

What is recreational mathematics? As the conference organizers write,

“Recreational Mathematics” is a problematic expression. For some people, like most professional mathematicians, Mathematics is lots of fun; but for others, like some students, Mathematics can be a nightmare. Historically, we know that some mathematical research areas are deeply linked to puzzles and games — probability and chance games, graph theory and the Bridges of Königsberg come to mind. Our Colloquium will be a Show and Tell of bright pearls of Mathematics, with varied levels of sophistication, entertaining many audiences. Its main goal is to foster mathematical appreciation, an important step if we are to see improvements in its practice.

The *Proceedings of the Third Recreational Mathematics Colloquium* are edited by Jorge Nuno Silva and compile eleven such pearls on a variety of topics. Most of the papers involve games and puzzles of various sorts, ranging from things you have likely heard of, such as Sudoku, to things you probably have not, such as Parallel. Many of the papers have a pedagogical flavor, discussing activities you could pull into the classroom or even do with children. One entry I particularly enjoyed was by Jorge Buescu and discusses the triangle puzzles first explored by Steve Humble. Robin Wilson has contributed a nice set of puzzles in Graph Theory, and Ricardo Cunha Teixeira, Susana Goulart Costa, and Vera Moniz have written an article illustrating the various symmetry patterns that arise throughout the tiles of the streets of São Miguel, Azores, the island where the conference was held.

The papers in this collection are written in a very informal style, and are very accessible. None of them contain particularly deep mathematics, but they are quite a bit of fun and give the reader something to think about, and isn’t that the whole idea of recreational mathematics?

Darren Glass is an Associate Professor at Gettysburg College. He can be reached at dglass@gettysburg.edu.