The purpose of this study was to develop an instrument for analysing elementary secondary school, and university science laboratory instructions. The categories of this analysis instrument were instituted through literature overviews and interactions with three researchers in a science classroom analyst team, a doctoral student, and eight master level students, who participated in the process of modification of the analysis instruments on the science laboratory instructions. The contents areas were divided into three categories: aims of laboratory activities, interactions, and scientific inquiry processes. Each category contains $2~3$ items. So the instrument consisted of 20 subcategories. The validity of the this instrument was achieved through checking with 4 science education specialists.