Timed Essay. I don’t know the topic yet.

I need a quick essay done in 15 minutes or 20. It only needs 4 paragraphs (5 sentences each). I don’t have yet the topic. I will have the topic on Wednesday. If it possible you should start the essay immediately after I have given you the subject. Please if you can finish the essay in 15 or 20 minutes . So i have the rest of the time to copy and turn in it my essay. My class is from 8:00 to 8:50 . My teacher wants this kind of essay .