This was evidenced by the fact that so few of you used the full time allotted to you. I'm not sure whether this was because you didn't rehearse your presentations or because you didn't do enough gathering of supporting evidence . In the future, I expect to see you using the full time, and using it well. In general, you find more evidence to support your claim. A claim is not evidence.
Evidence requires relying on external sources.
You might run experiments and summarize the results. You might look for information on the web or elsewhere. You might even synthesize information from what you've found. You also need to rehearse. One of you read a prepared speech.