This study aimed at investigating the effect of a portfolio strategy on acquiring the scientific concepts. The sample consists of 70 female students from the 3rd graders in Amman new camp school, distributed into two groups: experimental group and control group, a pretest of scientific concepts was applied on the two groups to find alternative concepts, after testing its psychometric properties using the suitable procedures, the experimental group has been taught one chapter in science using portfolio strategy and at the end of the experiment, the post test of scientific concepts was applied on the two groups The findings showed a significant effect of the portfolio strategy on acquiring scientific concepts. The study recommended applying portfolio strategy for the different grades, and conducting more similar researches on different grades and samples.