批改学生文章，常常会发现前后文关联不紧密，或者根本就没有关联的情况。有的时候甚至通篇文章下来都跟话题无关，而是朝着另一个方向在写。其实这些问题都源自于很多学生在写作文时思维跳跃性太大。中国人说话委婉，很多事情并不需要解释的很清楚，听众就能明白。然后美国人的思维却非常直接。他们更希望他人能够讲事情的每一层关系都讲清楚，这样才能帮助他们了解对方的意思。下面是从学生习作中挑出来的几个代表性的案例，我们一起来分析一下。
案例一：偷换概念
例题：Do you agree or disagree with the following statement? Teachers should assign homework for students every day.
这是机经上的一道题目，问是否同意“老师应该每天都给学生留作业”。这一题我们可以从every day着手，选择不同意的态度，首先让步——承认老师应该留作业，然后再转折——但是如果每门学科每天都留作业的话，对于学生而言负担太重，进而会造成一系列不好的影响。在初见这道题时，大多数同学都能想到上述的解题思路。可是在真正写作的过程中却有不少学生出现了“偷换概念”的情况：
开头段：I understand that the teachers need to assign homework. But now, teachers are giving too much homework. Every day, teenagers like us carry home loads of homework. It’s too much, that when we put it down, it almost can pile into an enormous book mountain. I think that some homework can be good for students themselves, but too much is not very efficient to kids.
中间段：(省略)主要论述作业多了如何不好
结尾段：At last, I suppose that giving kids an amount of homework is a good way to do, but giving them too much homework is very stressful. We all need nice rests, so the teachers need to give the students some breaks. The teachers need to handle both studying and resting very well.
开头结尾段表明的就是作者的观点和立场。从上面的学生习作的首尾段我们应该不难看出，他一直都在论述的是：现在的老师布置的作业太多了，老师不应该布置那么多的作业。回到我们的题目，题目里并没有提到“布置很多作业”，那小作者是怎么得到“作业很多”这个概念的呢?其实这就是因为作者思维上跳跃了一级：
assign homework every day→a large amount of homework→stressful for students
本文正确的行文应当是顺着上面的三个步骤进行推理，而作者却跳过了第一个步骤，直接从第二步开始，这样就导致整个文章偏离了话题的内容。虽然写的很有道理，得分却不高。那么对于这样的问题其实也有一个很简单的弥补办法，那就是在段首段尾加点料就行了。加点什么料呢?我们一起来看看下面修改后的版本：
开头段：I understand that the teachers need to assign homework. But now, teachers of all subjects are giving homework every day which seems too much for students to finish in one or two hours. Teenagers like us carry home loads of homework. When we put it down, it almost piles into an enormous book mountain. I think that some homework can be good for students themselves, but leaving homework every day will definitely lead to a heavy burden for students as too much assignment is not conducive to kids.
中间段：(省略)
结尾段：At last, I suppose that giving kids a certain amount of homework is good, but giving them homework every day will make them stressful because that will uplift the total amount of students’ daily assignment. We all need nice rests, so the teachers need to give the students some breaks.
上述修订版的文章保留了80%以上的原文，除了一些表达法的修订之外，就是增加了第一层关系：每天布置作业与作业量大的关系。虽然这层意思很简单，大家都能想到，但是在写作文的时候千万不能“高估”阅卷老师的智商，他们更希望什么都不用想就能知道你的文章跟题目是什么关系。所以，亲爱的同学们，抱着一颗将读者当傻瓜的心来练习托福写作吧，相信老师再也不用担心你偏题了!