How to evaluate peer????

In evaluating my friends, there are several criteria that must be taken into consideration. I have to evaluate them based on their performance; I mean the way they are presenting their lesson. I realize that it is very hard to evaluate people if we are actually at the lower level than them, or maybe just at the same level as they are. That is the problem that I faced when evaluating my friends as I think I’m not good enough to evaluate them but I try my best.
To be honest, what can I say is I think all of my friends (who has finished with their session) did great in their presentation. It can be seen through their performance during their presentation. They dress well; as the teacher for the whole class. Then they conduct the class very well in their own way to attract students. They are very great; in my eyes.
The activities provided also one of the items which must be seriously taken into consideration. Hmmm, I think they are good enough in creating their own ‘killing’ exercises..Huh, quite nervous until there is another person called to answer the questions; as long as that person is not ME.