  Automated feedback as students answer open-ended math questions has
significant potential in improving learning outcomes at large scale. A key part
of automated feedback systems is an error classification component, which
identifies student errors and enables appropriate, predefined feedback to be
deployed. Most existing approaches to error classification use a rule-based
method, which has limited capacity to generalize. Existing data-driven methods
avoid these limitations but specifically require mathematical expressions in
student responses to be parsed into syntax trees. This requirement is itself a
limitation, since student responses are not always syntactically valid and
cannot be converted into trees. In this work, we introduce a flexible method
for error classification using pre-trained large language models. We
demonstrate that our method can outperform existing methods in algebra error
classification, and is able to classify a larger set of student responses.
Additionally, we analyze common classification errors made by our method and
discuss limitations of automated error classification.
