Tarwyn, tell him that the first thing to do is check a trivial counter example, that is, to prove a theorem you must first be sure to check and see if it is false. In this case the theorem was, If p and q are distinct primes, p > q, and (a,p) = 1, then a^(p-1) is congruent to 1 (mod pq). This is in fact, a false theorem, for if we have
p = 3, q = 2, a = 4, then we have p,q distinct primes, p > q, and (a,p) = 1 , however, a^(p-1) = a^2 = 4^2 = 16 = 6 + 10 = 12 + 4 = 2*6 + 4 is congruent to 4 (mod 6) with
6 = 2*3 = pq.