First, I write "The Rules of English Class" on the blackboard and ask the students what it means. Then I ask students what they think the rules of English class are. I start out with an example:
Often the students follow up with "We must not speak Japanese." I usually write "We must bring our textbooks" to show that the verb "bring" is useful for classroom rules, and to emphasize that the rules are written about the class as a whole so the pronouns should be "we" and "our." After we've come up with about 5 rules for the class, I pass out the paper and ask the students to write down the rules we've all decided on.
After they've finished that, I put the students into groups (either pairs or groups of 3 or 4, depending on how big the class is and how well the students work together) and give each group a number. Then I write the numbers up on the board and assign each group a subject. For example:
For part 2, the students in the pair or group have to write the rules for that subject. So all of the students who are in group 1 write the rules of Social Studies class, students in group 2 write the rules of Japanese class, and so on. Having diverse examples in part 1 will help them come up with rules for part 2.
Once all the groups have enough rules written down, I ask them to appoint one representative and read their rules in front of the class. "What are the rules of math class?"
I'm sure your school has its own unique setting or grouping of subjects, so alter the activity as you see fit!