This study aims at investigating the effect of using two strategies- based Constructivist theory in teaching eighth grade students on academic achievement and the development of mathematical reasoning. The sample consists of (94) eighth grade students. It is randomly divided into three groups: the first experimental group is taught by adopting the Constructional learning model. The second experimental group is taught by adopting the learning cycle methods. the last is the control group that is taught by adopting the Traditional method. The study is conducted through two tools: the achievement test in mathematics, and mathematical reasoning test. The results show a difference of statistical significant at a level (α = 0.05) between the averages of students achievement of three study groups on Academic achievement and the development of mathematical reasoning tests. And this difference is attributed to the first experimental group and the second experimental group, respectively.