There is no reason why teachers should not write their own pro grammes, tailor-made to their own specific requirements. It takes time, but the teacher usually learns a great deal in the process. The principles of programmed learning can be used as a guide, and for linear pro grammes the book Programmed Learning in Perspective, referred to in the previous chapter, provides an excellent recipe. For those wishing to try their hand at writing a branching programme, Basically Branch- ing, by Rowntree, serves the same purpose.