AU - محمد، لمياء جلال AB - The current study aimed at detecting the effectiveness of the Flipped classroom in the development of some of the mathematical concepts among Educable mentally retarded students, and The study sample consisted of (20) male and female pupils who Educable mentally retarded students their ages between (9-12years) and of their intelligence percentage of (50-75) degree on the intelligence of the Stanford Benet scale. The researcher relied at the quasi-experimental method to measure the effectiveness of Flipped classroom for the development of some of the mathematical concepts among Educable Mentally retarded students, as for The experimental design of the study has used the ( one group pre- test, post- test ). then the researcher applied the pre- test on the study sample, then the researcher conduct experimental treatment to Flipped classroom pattern on the study sample then she applied cognitive achievement test after that she had conducted an appropriate statistical treatment using ( SPSS) program paired samples test. The results showed the effectiveness of the Flipped classroom in the development of some of the mathematical concepts among Educable mentally retarded students, can be traced to the fact that Flipped classroom strategy used useful technical , and the students learning better at the appropriate time and place for them, the study recommended to use the strategy inverted education in the education of some of the different subjects to people with special needs, as well as the training of special education teachers on how to implement Flipped classroom strategy. (Published abstract) http://search.shamaa.org/abstract_en.gif OP - ص ص. 439-466 T1 - فاعلیة الفصل المعكوس في تنمیة بعض المفاهیم الریاضیة لدى التلامیذ المتخلفین عقلیا القابلین للتعلم [مقال] UL - http://search.shamaa.org/PDF/Articles/EGAsep/AsepNo68P2Y2015/asep_2015_n68-p2_439-466.pdf النص الكامل (PDF) 1 http://search.shamaa.org/fulltext.gif