Better reading: A recent meta-analysis (Graham & Hebert, 2011) summarized dozens of studies examining the impact of writing instruction on reading comprehension. The authors concluded that there is a consistent, positive effect, and argued for three classroom practices.

First, more writing. (No surprise there.) Second, having students write about the texts that they read: for example, close analysis and interpretation, summaries, or the answering of questions, all of which demand understanding. Third, explicit teaching of the skills and processes that go into creating text. If students understand the conventions of writing an effective sentence, an effective paragraph, and an effective essay, then they will better understand how authors use those conventions. For example, they will understand that the start of a new paragraph likely signals the start of a new idea.

A writing assignment may guide student thinking toward substantive issues in, say, history, or it may guide students down a mental primrose path.



It's worth noting that these two advantages -- better writing and better reading -- will probably not accrue if most writing assignments consist of answering short questions, writing in journals, and completing worksheets -- exactly the writing tasks on which elementary school kids spend most of their time (Gilbert & Graham, 2010). Students need assignments that include writing in longer formats with some formal structural requirements.

Better thinking: There is a certain logic to the idea that students can become better critical thinkers by completing writing assignments. Writing forces you to organize your thoughts. Writing encourages you to try different ideas and combinations of ideas. Writing encourages you to select your words carefully. Writing holds the promise (and the threat) of a permanent record of your thoughts, and thus offers the motivation to order them carefully. And indeed some forms of writing--persuasive or expository essays for example -- explicitly call for carefully ordering thinking.

The foregoing logical case may be convincing, but the data are not. Efforts to use writing to teach subject matter have had mixed success (Bangert-Drowns, Hurley & Wilkinson, 2004).

That mixed record is likely due to the considerable diversity in how these programs were implemented and how "success" was measured. A writing assignment may guide student thinking toward substantive issues in, say, history, or it may guide students down a mental primrose path. Merely asking students to write about academic content is no guarantee of better learning; it must be a vehicle for students to engage in serious subject-matter work. Unfortunately, a recent survey (Kiuhara et al 2009) indicated that most high school students encounter writing assignments that typically do not demand this sort of analysis.