Nakisha and Samir are making an effective use of presentation skills. Both are defending their ideas and persuading the others to follow them, by showing their knowledge about the topic with examples, and making the other students agree with them by using their ideas as well.
Mark, Casey and Kara are not so effective as they are not approaching the conversation properly, paying close attention to the questions given, or defending their own opinion.
Mediagenic means tending to convey a favorable impression when reported by the media, especially by television
You forgot the period. And The capital "c". I don't know what type of question this is so I just helped with the grammar!
D. Walt Whitman is known for his use of imagery