In this contribution, we attempt to answer two research questions: (1) What effects do metacognitive questions have on students' writing skills? and (2) How do students respond to metacognitive questions? To answer these questions, we conducted an experiment with 43 students who were 11 to 12 years old. They were engaged in writing in a particular genre: book reviews. These pupils belonged to two classes at the same school, and for three weeks they experienced an instructional system combining identified principles of effective writing instruction, taught by the same teacher. They were required to rewrite their text several times, with the only difference being that in one group, metacognitive questions were introduced before, during, and after writing, unlike in the other class. A total of 172 written productions were analyzed under both conditions. Student responses in the metacognition condition were also analyzed. Our results show that students in both conditions made significant progress. But in the metacognitive condition, students made more significant progress.