The efficiency of a selected school textbook unit based on funds of knowledge theory in boosting five graders' academic performance and their attitudes towards the unit and towards their cultural identity and the unit's effect on learning retention in the Sultanate of Oman. This study aimed to explore the efficiency of a selected school textbook unit based on funds of knowledge theory in boosting five graders' academic performance and their attitudes towards their cultural identity and its effect on learning retention in the Sultanate of Oman. The study consisted of (28) female five graders from Al Jeela basic education school. The sample consisted of seven individuals from the students family members. For research purposes, the researcher used quasi-experimental and descriptive approaches to investigate through four research instruments. The first one was a semi-structured interview, which had four sections with 46 questions to obtain information on the participants' knowledge funds in agriculture. The second tool was an achievement test consisted of 30 questions. The same test was administered two weeks later to measure the participants' retention level of the information acquired. An attitude scale of 26 statements (in three main sections) was used to measure the participants' attitudes towards the cultural identity and a 24-statemnet scale (in four main sections) to measure their attitudes towards the selected unit. The validity of the research instruments was established through an instrument validation process carried out by expert judges. The reliability of the instruments was tested through conducting the reliability coefficient Cronbach's Alpha. The results are 7.31 for the achievement test, 0.789 for the cultural identity attitude scale and 0.916 for the attitude scale of the selected unit. These results indicates acceptable reliability of the instruments. Through analyzing the semi-structured interviews' findings, it is obvious that the participants had a considerable amount of agricultural knowledge and skills. The results shows a significant difference at (0.05=a) in the immediate post-test on academic achievement as the unit contributed to boosting the participants' academic performance. There is also a significant difference at (0.05=a) in the cultural identity attitude scale. The findings indicates very positive attitudes towards the suggested unit based on knowledge fund theory. In addition, a significant difference is shown at (0.05=a) in the delayed posttest on academic achievement. Based on these findings, the study has suggested a couple of recommendations pertinent to curriculum design and pre-service and in-service teacher education programs. It is also recommended conducting further research studies on knowledge fund theory in education, Utilization funds of Knowledge and involve families in the educational process .