John Walsh started teaching Biology and General Science in 1976 in St. Michael¹s Academy, Kilwinning, Ayrshire. He gained an additional teaching qualification in Computing, and began teaching Computing in 1986, and in 1991 was appointed to his present post of Principal Teacher of Computing in St. Andrew¹s Academy in Saltcoats, Ayrshire. He has considerable experience in working with the Scottish Examination Board (now SQA), first as a marker, then assistant examiner, assistant national development officer, working group secretary, panel member, moderator and vetter. In addition to the two textbooks already published, he has written various classroom support materials for Standard Grade and Higher Grade which have been distributed by the Scottish CCC (now Learning and Teaching Scotland), and materials for Higher Still which have been distributed by HSDU and SQA. He was appointed as a GTC Specialist Adviser in 1999, and is currently working on his third textbook for Hodder, Higher Computing.