Final answer:
The noun clause in the sentence is "what they did in the hall", and it is an object clause. Understanding clauses helps with proper grammar and usage of subject/verb agreement and personal pronouns.
Step-by-step explanation:
The noun clause in the sentence provided is "what they did in the hall", which functions as an object clause, as it is what the students got in trouble for. In grammar, a clause is a group of words that contains a subject and a verb. An independent clause can stand alone as a sentence, while a dependent clause cannot stand alone and is used within a sentence to provide additional information. It is important to understand the role of clauses to properly use subject/verb agreement and personal pronouns correctly.