PROS and CONS - prepare your arguments depending on which side you're supposed to be on (your teacher will tell you).
One of you will be the moderator and debate organizer: you make sure everybody speaks at least once, you ask someone who has been speaking for too long to conclude and let others speak, you boost the debate by asking new questions if nobody speaks for example.
In order to sound more convincing you may choose to embody a particular character:
an NRA member - a journalist working for a conservative newspaper - a crooked politician whose campaign was founded by arms industries - a historian defending the right to bear an arm base on historical facts - a citizen defending the 2nd Amendment - a person living in a dangerous area where the Police rarely go - an arms dealer - a teacher who welcomes the idea of having the right to carry a gun in class - a parent who thinks his/her child is not safe, not protected enough...
Or a teacher who does not agree with the idea of being given a weapon and having to learn to use it - a student who feels concerned about school shootings - a left-wing journalist or politician - a historian who believes times have changed or that the past needs to be interpreted differently - a citizen questioning the 2nd Amendment - a parent who is worried about guns being allowed in schools, or wondering about the easy access to weapons through the Internet...
In any case, check out statistics, crime rates, legislations in various states to use them as examples (quote your sources to sound more thorough), historical backgrounds, interpretations of the 2nd Amendment (Founding Fathers' intention): the fear of a strong government and what this has to do with gun ownership, etc...
ROLE PLAY - What is it? How do they spread? Does it really have an effect on people's view of "the truth"?
According to your part you will explain and defend your point of view: a TV anchor working for Fox News, a journalist for The New York Times, another for The Guardian (British), a blogger, a youtuber, a student, a teacher, a politician, a crooked politician, an MP, a twitter user, a historian specialized in communication and information through the ages, a philosopher, an engineer working for a social network, a hacker secretly working for Wikileaks, etc...
One of you will be the moderator and debate organizer: you make sure everybody speaks at least once, you ask someone who has been speaking for too long to conclude and let others speak, you boost the debate by asking new questions if nobody speaks for example.
In any case, define words and concepts, check out rates or statistics, look for examples. You might also need a timeline, a viewpoint on their influence upon past elections. Some keywords or expressions: fact-checking, alternative facts, post-truth, misinformation, debunk, discredit, deceive...