Nguyen, your approach to the prompt paraphrase / thesis statement is incorrect. The other problem, is that you added a discussion in the concluding summary that was unnecessary. The reasoning paragraphs are strong and well written though. Those are the major problems with your work. There are some minor issues as well that I will be pointing out in this review. Let me get into more details below.  
  
As I previously mentioned, your opening paraphrase has an incorrect approach to the discussion instruction. Unlike the comparison opinion essays, this is a direct question essay. For a direct question essay, you must present at least one direct response for each question. This will help you to better create your discussion outline for the reasoning paragraphs and also, offer the reader a quick insight into what the discussion you will be presenting is all about. So, rather than saying "This essay will...", you should instead be saying; "One of the possible causes of this problem are..." and "A doable solution can be found in..." as a response to both questions in individual sentence presentations as part of the prompt paraphrase.  
  
I also believe that you have a slight prompt deviation in the essay because you focused your paraphrase on teachers, when the proper synonym to use would have been educational institutions, faculty, or school house. Not teachers because they are not specifically mentioned in the paraphrase. The discipline of the student is an overall academic problem and not just a teacher's problem. However, that slight mistake did not take away from your effective reasoning so you can forget that for now. Just make sure you don't do it again in the future.  
  
A review of your concluding paragraph shows that you are closing the essay with a strong summary of the causes and solutions you presented. However, you added a personal opinion as the final sentence, which was based on a different topic that was not part of the original summary or given presentation. That was a personal opinion that was not required by the prompt and therefore, should not have been presented because it opened a new line of discussion which, as you very well know, cannot be done when presenting a concluding paragraph. Always review the prompt requirements and make sure to deliver only the required data. Don't add information that isn't specifically asked for because that could change the slant of your essay or, as in this case, create an open ended essay which means you did not effectively close your discussion.  
  
By the way, just as you should not write less than 250 words, you also should not write more than 300 words. At 448 words, you did not only write too many words but you ran out of time to actually write this essay. You also did not leave any time for you to review your content for clarity, cohesiveness, sentence structure, and other grammar related issues that may have an effect on your final score. Next time, write using a timer. If you are not done by the time the timer indicates the end of 30 minutes, you are writing too much information in the essay. You should use no more than 25 minutes for your draft. The last 5-10 minutes should be used for review and editing. That is the best way to improve your score.