Teachers of biology and related subjects are increasingly meeting objections from students and their parents to the teaching of evolution and the exclusion of what is called the theory of Intelligent Design. This paper attempts to draw together arguments and evidence which may be used by such teachers. Four lessons are drawn from the 1982 judgement against Creation Science in Arkansas for those opposing attempts to introduce the theory of Intelligent Design into school science programs: that a wide definition of science is the most useful; that religion is not the enemy; that science teachers should trust their own expertise; and that alternative theories should not be excluded. (Contains 17 notes.)