In the former case, you need to summarize all the studies. Again, be sure to define all relevant terms in your own words. Writing the Summary To avoid problems of unintentional plagiarism, I suggest that you put the article aside when actually writing up your summary. If you've taken notes as I suggested in the earlier section, you can use those notes to write your summary. Yes, it's plagiarism even if it's unintentional.
Some students benefit from writing an outline of the summary first.
Do this if you like. I will even look at the outline and give you my opinion on it if you show it to me at least a day before the paper's due. You also want to avoid writing the summary as you read because you will follow along with the article far too closely. Recall that this is meant to be a summary. You summarize the high points, with enough background info to help your friend understand what the article's about before hitting the major points you found of most relevance.