# High School Geometry/Authors
## Victor Cifarelli

Victor Cifarelli (Ph.D., Mathematics Education, Purdue University) is an Associate Professor of Mathematics and the Coordinator of the Mathematics Education Program in the Department of Mathematics at the University of North Carolina at Charlotte. His doctoral research focused on the role of reflective abstraction as a learning process in mathematical problem solving. His current research examines how solvers reflect on and test the viability of their evolving intuitions, and transform their initial hypotheses and conjectures into actual solution activity. Dr. Cifarelli has presented his research at AERA, PME, and PME-NA. His articles have appeared in the Journal of Mathematical Behavior, Focus on Learning Problems in Mathematics and the Proceedings of PME and PME-NA. Over the past several years, he has been an active contributor to SIG/RME as a reviewer and presenter of research papers. In addition to his research interests, Dr. Cifarelli has demonstrated an on-going commitment to the professional development of mathematics teachers. He has taught a variety of undergraduate and graduate mathematics and mathematics education courses including mathematics for elementary education majors, mathematics education for elementary and middle school education majors, and graduate mathematics courses for secondary mathematics teachers. He has co-directed a pair of projects for elementary, middle, and secondary grades mathematics teachers under the Eisenhower Professional Development Program and also has conducted numerous in-service workshops for middle grades and secondary mathematics teachers.

## Andrew Gloag

Andrew John Gloag was born in the North East of England and graduated from Oxford University in 1992 with a Bachelors degree in Physics. He obtained his PhD from Strathclyde University, Scotland in 1996 and worked in fiber-optics research until he moved to San Diego, California in 1999. He currently teaches physics and mathematics at High Tech High School in San Diego.

## Dan Greenberg

Dan Greenberg is author of 20 books for Scholastic Professional Books including Fabulous Fractions and Comic Strip Math, both of which have sold over 75,000 copies. Dan is currently working on True Tales of Deep Irony and Petty Vindication, a cartoon series that he hopes to turn into a book.

## Jim Sconyers

Jim taught secondary math from the East Coast to Hawaii and back to West Virginia. He worked with teachers and students from kindergarten through high school as a math/science specialist. Jim also spent several years creating and managing statewide math testing programs. Along the way Jim published many articles in math and science teacher journals, and he edited secondary math textbooks. Jim has a special interest in hands-on and project-based math learning.

## Bill Zahner

I am currently a doctoral candidate in mathematics education at the University of California, Santa Cruz. My research focuses on the ways students learn algebra through peer discussions, and the interactions between learning mathematics and learning language, with a special emphasis on understanding the mathematics learning of Latino English Learners. Prior to my exciting life as a graduate student, I taught high school math for six years--three years at Bellarmine College Preparatory in San Jose, and three years at Saramen Chuuk Academy in Chuuk, Federated States of Micronesia. While teaching in Chuuk, I first encountered the problem of finding appropriate and affordable texts for my students--and at that time I took the "do it yourself" approach and wrote an entire book based on my class notes. One of my hopes is that our CK12 books can be a resource for schools like the one I taught at in Chuuk. As an undergraduate I studied mathematics and computer science at Boston College, and I also worked with Jerry Keough and C.K. Cheung on the development of several texts for introducing Mathematica and Maple, and doing calculus with Mathematica. Beyond the world of mathematics texts, I am an avid cyclist, and an Oakland A's fan.