The society and environment teacher at the Kalgoorlie-Boulder Community High School asked the 10th standard student to pretend as terrorists and to plan a chemical or biological attack on "an unsuspecting Australian community."
The teacher instructed in the assignment, "Your goal is to kill the most innocent civilians in order to get your message across."
It also instructed the students that they had to explain their choice of victims and decide the best time and place to release their weapon.
But a student rejected to attend the assignment and gave a complaint to the principal of the school.
The assignment was withdrawn and the teacher counseled, but not before the issue was aired on talk back radio in Perth on Aug 25.
Principal Terry Martino said he had the task withdrawn as soon as he was aware of its content, and he had talked to the teacher.
He also claimed that the teacher was relatively inexperienced and had made a "well-intentioned but misguided attempt to engage the students".