Many teachers in junior schools will know the interest which children show in drawing patterns of multiples on a 10 × 10 lattice. If those for the primes 2, 3, 5, 7 and 11 are drawn on separate transparent sheets and are then superimposed, the picture produced by the overhead projector will have some of the appearances of a sieve. It will then be worthwhile to refer to an article by R. A. Fisher in Gazette XIV, 564–6 (No. 204, December 1929) which carries out the process in a slightly different way to reveal all the odd primes less than 1600, by drawing the factor lines of the primes up to p = 37; this same set will, of course, isolate all the primes less than 1681.