About the Author, Dan Umbarger
The author of Twenty Key Ideas in Beginning Calculus, Dan Umbarger, has taught various levels of mathematics from grade 5 to grade 12 for over 30 years. He currently is retired from teaching Computer Science. He is married and the proud father of three children: Jimmy, Terri, and Keelan. He is also the author of Explaining Logarithms and Explaining Bayes Theorem at www.mathlogarithms.com.