Once students have taken their initial positions, each group should discuss the evidence and reasoning supporting their claim. Then representatives from the different groups can present arguments for their positions to the whole class. The teacher or other students may ask questions to test the rationale for each position. Students should then be allowed to change position based on which arguments they find most persuasive. The class can then repeat this cycle of discussion, presentation, and repositioning.

As with the similar argument lines activity, the four corners activity works best when there are multiple plausible claims to be made about a topic. Rather than getting the whole class to agree on one "best" answer, the goal is to help students listen to each other, be able to explain fairly both those ideas they agree with and those they disagree with, and consider what kinds of evidence and arguments they find most persuasive.

It may be helpful to introduce this activity through non-scientific discussions first. For example, you might have the following claims: "dogs are the best pets," cats are the best pets," "fish are the best pets," and "birds are the best pets." Students who choose the dogs-are-best corner might confer with each other and then tell the whole class that dogs are the most affectionate pets and that walking dogs is good exercise for people. Someone from the bird contingent might counter that lots of people are allergic to dogs. But, retort the dog lovers, there are some dogs that are hypoallergenic. Well, say the fish fans, fish don't have to be fed every day, so you can go away for the weekend without getting a pet sitter; plus watching an aquarium full of fish is very peaceful...