The aim of the research is to identify the effect of a scenario-based learning in the mathematics achievement and the mental motivation for fifth - scientific grade students in high school. To achieve it, the researchers adopted the experimental research method with two groups (experimental and control) with a post-test. The research community was identified, which represents the fifth scientific grade students from the first Karkh Education Directorate. The sample (60) students were chosen intentionally, and was divided into two groups: an experimental group that studied according to the scenario-based learning model; and a control group studied according to the usual method. For the purpose of collecting data for the experiment, the achievement test was built, in its final form, consisting of (10) test items of the type of essay, and the mental motivation scale, in its final form, consisting of (60) items. Appropriate statistical analyzes were conducted, and the psychometric properties of the test and scale were confirmed. The results indicated that the students of the experimental group who studied according to the scenario-based learning model outperformed the students of the control group who studied according to the traditional method.