Abstract: A grammar teaching system provides adaptive practice to build students' grammar skills with respect to verb tense errors. The system displays a sentence to a user, and allows the user to identify the locations of verbs within the sentence and tenses of the identified verbs. The system reinforces correct designations of verbs using visual cues. If a user incorrectly identifies a term as a verb within a sentence, then the system displays information to help the user understand the nature of the incorrectly designated term. The system allows the user to determine whether the sentence includes a verb tense error and to select a particular verb in the sentence to replace in order to correct any verb tense error. The system allows the user to obtain help in correcting a verb tense error by providing optional tasks that step the user through the reasoning needed to correct the error.