But when a teacher tries to give students a practical demonstration, guess what happens? Yes, they get found guilty of professional misconduct by the General Teaching Council (GTC).
Fiona Foster, a supply teacher, was caught charging pupils 50p each to make Mother's Day cards.
The exercise was not even part of the curriculum at Wilmington Enterprise College in Kent, yet the teacher managed to get her pupils to cough up their money by telling them the materials had cost her pound;12.99. And this was not the first time Mrs Forster had parted children from their pocket money. She was previously banned from teaching for six months after being caught selling cigarettes to pupils at Meopham School in Kent in 2006.
The GTC has yet to decide what her punishment should be for her activities at Wilmington, where she was also accused of making inappropriate comments to her pupils.