The study aimed to build a proposed teaching model based on the similarities strategy and to identify the effectiveness of its use in teaching mathematics in developing mathematical thinking among third-grade students.

The study tested the following hypothesis:
- There are statistically significant differences between averages of scores of students of the experimental and control groups in the mathematical thinking test afterwards and in favor of the experimental group.
    To achieve the study objectives, the researcher adopted the semi-experimental curriculum, and the sample of the study, consisting of (42) students, was chosen from the third elementary students of the Saudi Primary School in the Laith Education Zone, and they were divided into two groups, one of which is a pilot consisting of (21) students studied using the proposed model, and the other is a control consisting of (21) students studied By the usual way, during the second semester of the academic year 1440/1441 AH. The researcher prepared a test in mathematical thinking, and his honesty and reliability were verified, then it was applied to the two research groups beforehand to make sure the two groups are equal, and then to verify the effectiveness of the proposed model.
The study reached to the following results:
1)        Building a procedural teaching model to use the similarities strategy in math teaching.
2)        The study showed the effectiveness of using the proposed teaching model in developing mathematical thinking for third-grade primary students with an impact size of (0.48).
3)   There are statistically significant differences at the level of (≤ 0.05) between the mean scores of the control group that were studied in the usual way, and the experimental group that was studied using the proposed teaching model in the post-application of the total score in the mathematical thinking test, and the differences were in favor of the experimental group.

In light of its results, the study recommended several recommendations, including:

1)   Benefiting from the suggested model in applying the similarities strategy in teaching mathematics in the elementary stage, and in the rest of the academic levels in general education.
2)   Holding training courses for mathematics teachers on using the similarity strategy in teaching.
3)   Include new programs to prepare the teacher with modern strategies emanating from structural theory, such as the similarities strategy, to reach their impact for students and learn about their theoretical foundations and methods of application.