Abstract

• Nowadays, the application of equivalent test forms has been increasingly interested in many testing situations because it can produce fair and equitable test scores for every student. In Myanmar, in accordance with changing in the curriculum, fair and square testing sites need to be constructed with the use of equivalent test forms. Therefore, in this paper, two equivalent forms of Grade Six science achievement tests were built. To develop the tests, a two-parameter logistic model (2PLM) of item response theory (IRT) was utilized. The two test forms were administered to the 1002 students from selected eight schools in Yangon Region in last week of September. Consequently, the responses of students were scored and two test forms composed of 25 items were equated with the use of equate IRT package in RStudio.