"From their day of qualification a teacher can be asked to teach almost anything" (TES, Letters, March 20). Not long before my first chemistry lesson as a newly-qualified teacher the head burst into my laboratory and said: "We shouldn't have advertised for a chemist - it should have been a biologist."
For two years I taught biology by the seat of my pants, by being one page ahead in the textbook, with the support of a laboratory technican. The school then appointed another chemistry teacher.
Survival in a subject is deemed sufficient qualification to teach it for 14 years.
DENNIS SINCLAIR, 5 Alexandra Road, Pudsey, West Yorkshire