In order to determine students' achievement, science teachers have to develop their own assessment tools. This study attempts to find out the relationship between the teachers' assessment tools and students' cognitive development according to the teachers' teaching experiences. Six open-ended survey questions were developed and delivered to 59 middle school science teachers. It was clear that the majority of science teachers used only written and oral assessment tools. Regardless of teaching experiences, almost all the samples do not have detailed knowledge on students' cognitive development and its relation to asking questions. (Contains 6 tables.)