The present study aims to measure the effect of fryer model on grammar achievement and retention of this achievement for grade sixth students in sultanate of Oman. The researcher prepared a special booklet that contained guidelines on how to inprove student achievement using Frayar model strategy as well a grammar achievement test. A specialist jury validated both the test and the booklet. The reliability of the test was found to be 0.73 using cronbachds alpha. The sample of the study included tow groups; The experimental group which had 31 students who studied Arabic grammar using Frayar Model and a control group that 31 students who studied grammar in the regular conventional way. A post test was administered to both groups right after the experiment to assess students grammar achievement and tow weeks later to assess retention. The study results revealed variance of atistically significance at a< 0,05 between the averages of the tow groups in favor of the experimental group. The study also didn't show astatically significant difference between the mean score of the groups in the delayed test for the experimental group at a level of a< 0,05. Based on the results stated above, the researcher makes a number of recommendations. One of these is that it is important to train Arabic teachers on how to use Frayer Model strategy not only to reach Arabic grammar but also other branches of the subject such as rhetoric and spelling.