Comparing common mathematical errors to correct examples may facilitate learning, even for students with limited prior domain knowledge. We examined whether studying incorrect and correct examples was more effective than studying two correct examples across prior knowledge levels. Fourth- and fifth-grade students (N = 74) learned about decimal magnitude in a brief tutoring session. Students were randomly assigned to two conditions: 1) comparing correct and incorrect examples ("incorrect" condition) or 2) comparing correct examples only ("correct" condition). The "incorrect" condition helped students learn correct procedures and key concepts more than the "correct" condition, including reducing misconceptions. Students' prior knowledge of decimals did not interact with condition. Students' explanations during the intervention revealed that those in the "incorrect" condition more frequently discussed correct concepts (e.g., the magnitude of a decimal and identifying misconceptions). Overall, contrasting incorrect examples with correct examples can help students learn correct concepts and procedures. (Contains 3 tables and 1 figure.)