“The effectiveness of combining the “Needham” Constructivist Model and Gardens of Ideas Strategy in Developing Mathematical Proficiency among primary school Pupils” Abstract: The research aimed to measure the effectiveness of combining the “Needham” Constructivist Model and Gardens of Ideas Strategy in Developing Mathematical Proficiency among primary school Pupils. The experimental method was used; The research sample was selected from sixth grade primary school pupils at (AL-Shahid Ahmed Abdullah Al-Zaqqaqi) School in Mit Ghamr Educational Administration/Dakahlia Governorate; and it was divided into: an experimental group (n = 45), and a control group (n = 45). The research prepared a test mathematical proficiency (the first four dimensions), and a scale of productive mathematical disposition (the fifth dimension thereof), which were applied pre- and post-test to the two research groups. After the experimental treatment and testing the validity of the hypotheses, the results showed: There is a statistically significant difference between the average scores of the students in the experimental group and the scores of the students in the control group in the post-application test for the mathematical proficiency in favor of the students in the experimental group, and the presence of a statistically significant difference between the average scores of the students in the experimental group and the scores of the students in the control group In the post-application of the scale of productive mathematical disposition for the benefit of the experimental group students; That is, the combining the “Needham” Constructivist Model and Gardens of Ideas Strategy led to the development of mathematical proficiency in its five dimensions among the pupils of the research sample. The results did not reveal There was a statistically significant difference between the average scores of the experimental group’s students in the two applications (post and follow-up) of the mathematical proficiency test and the productive mathematical disposition scale. Which indicates the continued effectiveness of the combining the “Needham” Constructivist Model and Gardens of Ideas Strategy in developing the dimensions of mathematical proficiency as a whole. Keywords: “Needham” constructive model- Gardens of Ideas strategy- Mathematical Proficiency.