Be a good teacher.
Check understanding.
Never ask your pupils the following question after or during a lesson:
'Have you understood?' 'Ok?'
Your pupils may answer ' yes' without understanding anything.
The ideal solution is to ask them 'concept questions' so that you can assess how many have understood and how much they have understood.
For further knowledge go to:
CONCEPT QUESTIONS.
http://www.teachingenglish.org.uk/think/articles/checking-understanding
CONVEYING MEANING
http://www.teachingenglish.org.uk/think/articles/conveying-meaning
Mohamed07