Five experiments showed how writing contributed to knowledge acquisition of probability and critical reading of a short research paper. In learning probability writing to relate laws of probability to their example events made students solve practical problems more successfully than internally generating relations and being given their descriptions. Writing was proved to promote constructing a situational model of the probability while reading the text. In critical reading of an article, writing brief summaries of its research problem, method, results, and discussion, and whether they are reasonable or not was more effective in generating critical comments than orally performing the same requirements. The students interactively read and wrote, sometimes reported questions, and then began to search answers or clarify how their questions affected the research. Writing brought about problem solving process in reading a text and produced an extended and integrated internal-external cognitive place in which products of real-time cognitive activities were directly visible and available. Meta-cognitive activities would work better in such a constructive and visible problem solving space.