http://waygook.org/index.php/topic,16567.msg131478.html#msg131478

This is the link for a writing textbook that my colleagues and I did for our second grade high school students.  It builds up to writing an academic essay.  Please excuse the typing errors that eluded me during the editing stages. 

If you have an ESL bookstore near you, look for "From Great Paragraphs to Great Essays" by Folse, Vestri Solomon and Clabeaux (ISBN 978 1 4240 7113 5) by Heinle Cengage Learning.  It's book 3 of the "Great Writing Series".  Book 4 is also god: "Great Essays" by Folse, Muchmore-Vokoun and Vestri Solomon (ISBN 978 1 4240 7113 2).

I teach a writing class at my middleschool. I found it useful to build up their confidence working on sentence structure, and am now teaching them about paragraphs. After a lesson or two on this, depending on their progress, I will move onto full essays. Depending on the level of your students, my ppt and worksheet may be of use.
Also, this link : http://writing.pppst.com/paragraphs.html was useful.

I would strongly recommend more than "a lesson or two" on paragraph structure.  Topic sentences take at least one lesson to master as does the idea of concluding sentences.  Understanding the function of supporting sentences and inking ideas takes at least 2 - 3 lessons.  Putting all of these together into a paragraph is another 3 - 4 lessons (they need time to plan, write, revise, peer edit, final edit). 

In every writing course I've led (first language, ESL, postgraduate, high school and university), I've found that students need a lesson for planning, a lesson for writing, half a lesson for editing/revising, half a lesson for peer editing - all for one paragraph.  Also, you need to teach general paragraph structure (at least 4 lessons - more if they're ESL students), introductory paragraphs (at least a lesson) and concluding paragraphs (at least a sentence) before moving onto an essay.  I would break up the essay into these parts and have students write the introductory and concluding paragraphs first, then move onto the body, then editing, use a checklist for peer editing and ask the students to identify things like the main points in each paragraph, the final idea, etc. in the peer edit.