Subject verb agreement is one of the most common English grammar errors made by English language learners as well as native speakers.

Agreement Error is a free English grammar app that can help learners practice identifying if subjects and verbs agree. Random sentences with correct and incorrect agreements are created using a natural language generation algorithm. The user determines if the sentence grammar is correct or not. After a sequences of questions users can review their answers. Additionally, users can review the parts of speech such as nouns, verbs, etc. tagged to each word in the practice sentences to help them identify the words essential to correct subject verb agreement.