Pronouns help us communicate concisely. Correctly identifying an antecedent with a pronoun is not always easy even for good communicators, particularly when there are multiple characters or proper nouns to keep track of.
This lesson teaches students how to identify the antecedent in a sentence (try replacing a noun with a pronoun until it makes sense).
A fun story involving aliens is weaved throughout the lesson to give students opportunities to practice pronoun-antecedent agreement.