A lot of my work with curriculum development and pedagogical technology bleed into the area of recreational mathematics, which I have always found to be an engaging way to introduce mathematical ideas. As a long time fan of Martin Gardner from the points of view of both mathematics and magic, many of the items below are connected with things I read in his books and articles.

- The page of supplementary material for my textbook in Discrete Mathematics.
- Envelope of Lines, an ongoing collaboration with Dan Kalman of American University
- Envelope of Lines 2, the sage continues...
- Envelope of Lines 3, a new hope...
- Envelope of Lines, final version on the book site for Dan Kalman's
*Uncommon Mathematical Excursions: Polynomia and Related Realms*, published by the MAA. - Applet and Information on the Leapin' Lizards puzzle
- The
following applets on "Rick Wilson's Tricky Six puzzle" supplement the
paper by Richard Guy and Alex Fink in the April 2009 issue of
Mathematics Magazine:
- Practicing the moves on pages 85-86 of the article.
- Trying the puzzle using the description on page 85 of the article. This is harder than you think!
- Illustrating the puzzle described in the last paragraph of the article. This also ties in with the cover image for this issue of Mathematics Magazine.

- A collection of applets for Math for Liberal Studies, developed with James Hamblin as part of a 2009 grant from the PA State System of Higher Education Faculty Professional Development Council.
- A Mathematical Card Trick that you can do easily with your own cards.
- A combinatorial card puzzle from the article "Combinatorial Card Problems" from Martin Gardner's
*Time Travel and other Mathematical Bewilderments*. - This presentation for Celebration of Mind at Shippensburg University in 2010 uses some of the applets below.
- John Conway's game of TopSwops, written to accompany the article "Combinatorial Card Problems" from Martin Gardner's
*Time Travel and other Mathematical Bewilderments*. - The Two Player version of John Conway's game of TopSwops, written to accompany the article "Combinatorial Card Problems" from Martin Gardner's
*Time Travel and other Mathematical Bewilderments*. - John Conway's game of BotDrops, written to accompany the article "Combinatorial Card Problems" from Martin Gardner's
*Time Travel and other Mathematical Bewilderments*. - My Graph Slider puzzle which has a mobile version in the Android Market
- My Fifteen Puzzle to illustrate permutations in this kind of puzzle.

## Contact InformationDoug Ensley, Ph.D.Deputy Executive Director Mathematical Association of America 1529 18th St. NW Washington, DC 20036 Phone: 202.319.8464E-mail: densley at maa.orgWeb: http://webspace.ship.edu/deensley/or http://www.dougensley.com |