<![CDATA[This research aims to identify the effect of an instructional design based on Needham's constructivist model on developing the cognitive depth of fifth-grade science students in mathematics. To achieve this objective, the researcher adopted a quasi-experimental design with two equivalent groups (experimental and control) using post-tests, as this approach was deemed most suitable for the nature and objectives of the research. The research population consisted of fifth-grade science students in secondary and preparatory schools affiliated with the General Directorate of Education in Salah al-Din Governorate during the 2025-2026 academic year. The research sample was selected purposively and comprised 64 students, equally divided into two groups: an experimental group of 32 students who were taught using the instructional design based on Needham's constructivist model, and a control group of 32 students who were taught using the traditional method. The researcher ensured the equivalence of the two groups in several variables that could influence the results of the experiment.To measure cognitive depth, the researcher developed a test consisting of 30 objective items, distributed according to the levels of cognitive depth. Its validity was verified by presenting it to a panel of experts and specialists. Its psychometric properties were also determined, including difficulty and discrimination indices and the effectiveness of the alternatives. Furthermore, its reliability was confirmed using appropriate statistical methods. The experiment continued during the first semester of the 2025-2026 academic year. A post-test was then administered to the students in both groups, and the data were statistically analyzed using the Statistical Package for the Social Sciences (SPSS), employing an independent samples t-test at a significance level of 0.05.The research results showed a statistically significant difference between the mean scores of the experimental and control groups on the cognitive depth test, favoring the experimental group, thus indicating the effectiveness of the design]]>
