First; read briefly this article and discuss it in general with your group: http://mashable.com/2013/08/18/social-media-teachers/
1- Do not interrupt the debater until he finishes what he wants to say.
2- Finish what do you want to say in -at most- 2 minutes.
3- Respect each other.
Homework: write a short article about which is better to teach students: textbooks or social networks? Give at least reasons for your choice.