Abstract
This study aims at investigating the effectiveness of the cooperative inquiry strategy in developing the achievement and development of mathematical communication skills of elementary school students. To achieve this aim, the experimental method was utilized. The study sample consisted of an experimental group (n = 34) and a control group (n = 31), which were randomly selected from primary schools. A Teacher's Guide for teaching a unit entitled "Statistics and Graphic Representations" for the sixth elementary graders in the first semester were devised. A (30) multiple-choice item achievement test distributed at the levels of (recall, comprehension, and application), as well as an (18) item mathematical communication skills test including (mathematical representation, assessment of thinking paths, and mathematical writing) were also devised. The test questions included completion, short essay, and mathematical problem-solving questions. Both the study tools were statistically validated. Experimentation was carried out during the first semester of the academic year (1439/1440 AH). The results of the study revealed that there were statistically significant differences at the level of (0.01) between the mean scores of the students of the experimental and control groups in the achievement test post-testing favoring the experimental group students. The results also revealed that there were statistically significant differences at the level of (0.01) between the mean scores of the students of the experimental and control groups in the mathematical communication skills post-testing favoring the experimental group students. A positive correlation was also revealed between the post-testing scores of the experimental group students in the achievement and the mathematical communication skills tests. In light of these results, some recommendations and suggestions for further research were presented.