The aim of this research is to investigate the effect of education on the mathematical achievement, problem-solving skills and the views of students on the 5E instructional model and the mathematical modelling method for the “Geometric Objects” unit. The students were randomly selected from the 8th grade of a secondary school in Northern Cyprus. One group was the experimental group to which the 5E instructional model applied, and mathematical modelling was applied to the other. As a data collection tool, the “Geometrical Objects Multiple Choice Achievement Test” was applied to the experimental groups. As a result of statistical analysis, it was seen that the teaching provided by the 5E Instructional Model in Experimental group 1 and the Mathematical Modelling Method in the Experimental group 2 increased the academic achievement of the students; however, the mathematical modelling method was more successful in the mathematical achievement and problem-solving skills of the students.