Since the passing of Law No. 2 of 1989, the landscape of education in Indonesia should be distinguished by the consistency of its system, thus by a series of adjustments. Some possible adjustments to the primary school curriculum to the high school level include (1) imbalances in the effective learning offered. This is supported by the fact that, since the implementation of the national exam (in elementary schools), the field of mathematics studies has one of the lowest average values among national exam subjects. (2) The ongoing curriculum's requirements not fit with students intellectual development. This study will employ theory of learning based on Piaget's intellectual development from a variety of learning theories based on cognitive theory. According to Piaget's hypothesis, a child's development progresses over the course of 4 sequential phases, consisting :(1) Sensory motor period (ages 0 to 2 years), (2) per-operational period (ages 2 to 7 years), (3) concrete operational period (ages 7 to 11 years), and (4) formal operational period (ages 11 and onwards).The purpose of this research is to determine the level of effectiveness in teaching geometry unit math based on the conservation aspects of Piaget's theory. These goals can be summarized as follows: 1) Determining the amount of efficacy in teaching geometry unit math using Piaget's theory's conservation components;2) Identifying differences in the influence of age (9, 10, and 11) on receiving geometry unit math teachings based on the conservative aspects of Piaget's theory. To accomplish the study's objectives, the research utilized a per-experimental research design, particularly a pre-test-post-test design with one group. The results indicated that the learning accomplishment of geometry unit math based on the conservation aspects of Piaget's theory did not vary by age (9, 10, or 11 years). The study's findings indicate that there is no interaction effect between the ages of 9 and 10 on math learning achievement, (2.2) that there is no interaction effect between the ages of 9 and 11 on math learning achievement, (2.3) there is no interaction effect between the ages of 10 and 11 on math learning achievement, and (2.4) that there is no interaction effect between the ages of 9 and 10 on math learning achievement. Keywords: Mathematics, elementary school.