Many of us teachers strongly recommend that our students write. Why? Because writing will help you ‘visualize’ your thoughts. And your learning will accelerate drastically. Writing gives structure to the thinking process. When engaged in the act of writing, the feedback between reading and writing develops instantaneous thought-visualizing skills. Composers know that.
This visualization before speaking allows the analytical mind to anticipate potential problems and formulate options. In the learning process, it clarifies grammatical problems. Forms idiosyncratic to the new language will make sense.
And for those proud of their cognitive skills, it opens possibilities of greater sophistication when speaking.
For intermediate to advanced students, I suggest finding an article you like and do a summary or a review of it, with your opinion. Because at the same time you’re writing your thoughts, you begin to absorb and analyze how native writers think.
Writing 2-3 paragraphs will do wonders, especially if done daily. This could be in the form of a journal, a summary a typical day, a recent holiday or a dream vacation, hobby pursuits, etc. – any little story really.
The most important thing is to project your thoughts into real life. This makes it directly relevant to each individual’s interests, motives, or tastes. You will be more readily prepared when confronted with similar everyday situations, when faced with native speakers.
There are some students however (pure ‘action types’ let’s say) with whom I don’t push writing exercises. But for the majority, even a little writing every day goes a long way. Once the habit is formed, you will realize it’s actually an enjoyable experience to write. And you will begin reaping many benefits – especially with the feedback of a teacher.