Here's why:
* Predicate: The predicate is the part of a sentence that tells us what the subject does or is.
* Complete Predicate: The complete predicate includes the verb and all its modifiers (words or phrases that describe the verb).
In this sentence, the subject is "Everyone in your school" and the verb is "wearing." The phrase "uniforms this year" acts as a modifier, telling us *what* they are wearing and *when*.