摘要:The aim of this study is to develop a valid and reliable scale for assessing students’ achievement in English classes on Simple Past Tense. Firstly, to ensure the content validity expert views were taken into consideration at every stage of the study. Experts were composed of nine English teachers and four curriculum instructors. Secondly, 130 questions were gathered from nine English teachers. 55 questions, which were thought to be testing the same goal, were eliminated and 75 questions were left for pilot study after the opinions of experts. A Pilot study was conducted with 75 questions and 266 students who are in 12th grade. The students were chosen from four different high schools. The final form of the test consisted of 25 questions. After the application, the data were analyzed with ITEMAN and SPSS. The analysis revealed reliability coefficient (Cronbach Alpha) as 0.81, mean difficulty as 0.54, mean discrimination as 0.36, Spearman Brown Correlation as 0.89. Item total correlation ranged from 0.38 to 0.63. Based on the data obtained, the Simple Past Tense Achievement Test (SPTAT) can be said to be reliable and valid tool to assess students’ achievement in English classes on Simple Past Tense.