Abstract: Techniques are described for an automated grammar teaching system that displays sentences and allows a user to identify parallel structure errors within the sentences, if any. The user may be asked to determine whether the sentences have a parallel structure error, to identify the items that should be made parallel in structure, to select items to be changed from the identified items, and to provide corrections to the selected items so that all the items form consistent parallel structures. Multiple parallel structures may be valid and accepted as correct for a given parallel structure error. To guide the user, user responses may trigger the display of remediation information, which may include reasons why the selected items are incorrect. New sentences in the teaching system may be selected based on historical data maintained for the user.