Meet with the students that are struggling and guide them through the process of writing an essay. Get out a sheet of paper and divide it into three sections (although make the middle section larger than the other two). Label these "introduction," "body" and "conclusion." Use this and help them make bullet points about what they are going to say in each of these sections.
Begin with the introductory paragraph and encourage them to think about what their topic sentence will cover. Make sure it covers the topic of the paper and presents a strong argument. Tell them the topic sentence is just a sentence that explains briefly what they will be discussing in the rest of the paper. Have them write this under the "introduction" section.
Move on to the body of the essay. The body needs supporting evidence from an outside source. They can make bullet points for now on the same sheet under "body."
Finish with the conclusion and let them try to say it in their own words. It should effectively summarize the rest of the paper and restate the thesis or topic sentence. This needs to go under "conclusion."
Tell them to write the essay using the sheet you helped them with. It is easier to use the sheet because it will have their thoughts complete and organized. All it will need is a little elaboration.