A comparison was made of the effectiveness of a simulation-type inservice education program on teacher awareness of pupils' instructional reading levels in relation to the time of school year that the inservice program was conducted. Specific simulation processes, including sound films, audio tapes, overhead transparencies, and instructional booklets, provided teachers with a knowledge of, and the ability to administer, an informal reading inventory. A three-group-post-test-only control group research design utilized three stratified random samples of 32 teachers each from grades 2 through 5 in a large suburban school district. Pupils were randomly selected from each teacher's classroom. Differences between the grade level of pupils' readers and their performance on McCracken's Standard Reading Inventory constituted the measure of teacher awareness. Findings indicated that this inservice program was effective only when conducted before school begins. Those teachers who participated in the program later in the school year were no more aware of pupils' instructional levels than those who did not participate. References are included. (Author/CM)