This quasi - experimental study has aimed to suggest a unit based on activities and explore its effectiveness on the achievement of third preparatory class in history subject. The sample of the study consisted of (4) classes, which were randomly chosen from Qaba and Subaki School. The two third preparatory classes from Qaba School were used as an experimental group and taught through activities approach. The other two third preparatory classes from Subaki School were used as a control group and taught through traditional method. To measure the effectiveness of the unit the researcher built an achievement test and obtained it prior to and after the study. The results of pre test have indicated that there were no significant differences in mean achievement between the experimental and the control group. The results of the post test have shown the existence of significant differences at level (a= ,01 ) in mean achievement between the experimental and the control group in favor to experimental group, there were also, significant differences at level (a=,01 )in mean achievement in Comprehension, Application, Analysis, Synthesis, and Evaluation levels between the experimental and the control group in favor to experimental group, and there were no significant differences at level (a=,05 )in mean achievement in Knowledge level between the experimental and the control group. According to the results of the study the researcher conducted many recommendations in curriculum, evaluation, training teachers , teaching and local environments. The researcher recommends additional studies.