Writing Team

Angie Seltzer has 30+ years of experience in math curriculum writing, editing, and instructional design. She has been a supervising editor of major textbooks, assessment resources, and technology supplements. Angie has taught at the middle school level and tutored students of all ages. She has a master's degree in mathematics education from The Ohio State University. www.linkedin.com/in/angie-seltzer

David Spangler has been active in mathematics education since 1972. He has taught at the middle school and community college levels — while continuing to teach math methods courses at the university level. In 1994, he co-founded ActiveMath Workshops for teachers (www.activemath.com). Over the years, he helped develop math programs for major publishers, has authored seven math books, written numerous math articles for math education journals, and has been a frequent speaker at math conferences. David holds a master's degree in education with an emphasis in mathematics from Northern Illinois University. www.linkedin.com/in/davidbspangler

Karen S. Cordell has been a trusted math educator/coach/consultant for 35 years. Her focus is development of resources that support efficacy, access, and equity for all students. She has taught middle school and high school mathematics and has planned and delivered engaging lessons that helped all students build conceptual understanding through varied reflective learning activities. Karen has created both formative and summative assessments. Her master's degree in educational leadership is from The College of New Jersey. www.linkedin.com/in/karencordell 

Contributions by David, Karen, and Angie to this Store
  • Angie has written and designed hundreds of versatile math games that can help all students develop math sense. She has also written student-friendly math goals and related assessments for easily tracking student progress. 
  • David and Karen are the co-authors of more than 130 Math History-Mystery Puzzles. These engaging warm-up puzzles for middle school students connect mathematics to people and events through history. The clues in each puzzle provide review of a wide range of topics, making the puzzles ideal for test prep.
  • Angie has designed the covers, previews, correlation charts, and other elements for Math History-Mystery Puzzles. She is also the webmaster and designer of this educational resources store.