We investigate whether erroneous examples in the domain of fractions can help students learn from common errors of other students presented in a computer-based system. Presenting the errors of others could spare students the embarrassment and demotivation of confronting their own errors. We conducted lab and school studies with students of different grade levels to measure the effects of learning with erroneous examples. We report results that compare the learning gains of three conditions: a control condition, an experimental condition in which students were presented with erroneous examples without help, and an experimental condition in which students were provided with additional error detection and correction help. Our results indicate significant metacognitive learning gains of erroneous examples for lower-grade students, as well as cognitive and conceptual learning gains for higher-grade students when additional help is provided with the erroneous examples, but not for middle-grade students.