This booklet is a catalog of error patterns found in basic arithmetic and algebra courses. It is intended to be used as a resource by instructors and tutors teaching these concepts. The material is divided into major concept headings with subheadings. The error patterns are named and given a brief general description followed by a specific example of the error. Major concept headings include the following: (1) Basic Problem Solving Skills; (2) Averages; (3) Whole Numbers; (4) Fractions; (5) Decimals; (6) Percents; (7) Integers; (8) Exponents; (9) Simple Equations; (10) Ratios and Proportions; (11) Geometry; and (12) Graphing. (RH)