Sometimes English can be so tricky. Take an easy word like 'watch.' Recently, as a student was leaving the bus from the front end, the bus driver advised, 'Watch your step.' The student, therefore, paused at the door waiting for the hydraulically operated steps to unfold. After the steps were locked into place and the door was wide open, the driver repeated, 'Watch your step...'
Thinking that this expression meant 'wait a minute,' the student didn't move, so the bus driver again said, 'Watch your step...' By now, the student was getting a bit annoyed. The steps WERE down, and it was not obvious why the student should wait to get off the bus. What should he say? What should he do?
Finally, the bus driver repeated the expression,'Watch your step.' This time the student impatiently replied, 'I AM watching the step!' To the student's surprise, however, the bus driver shook her head in disgust, remarking 'Never mind....' At that point, the student realized he'd misunderstood and, blushing with embarrassment, quickly got off the bus.
At our private lesson later on, I explained some of the many uses of 'watch':
'Watch out!' (Pay attention! Something dangerous could happen.)
'Watch your head.' (Someone might say this to you so that you don't hit your head on a low entryway.)
'Watch your language!', or 'Watch what you say!' (Be careful of the words that you use in speaking. Don't be rude or inconsiderate when you speak.)
'Watch your speed.' (It seems like you're driving too fast, so slow down. Or, maybe you just saw a highway patrolman, and your friend was speeding. You don't want to get a ticket.)
'Watch what you're doing.' (Pay attention to what you are doing.) and so on.
The great thing about listening and 'watching' what people are saying to you - catching these little expressions and actively engaging in an interaction using these kinds of new phrases - is that you can learn a great deal of colloquial English by doing so. Add in a measure of stress and embarrassment, and you ensure that you will NEVER forget the meanings of these expressions.
So, get out there, ESL students, and pay attention to the phrases that people often use. Stick your neck out (meaning, 'take chances/risks'). There are boundless opportunities to learn English. Watch out for them. You can encounter an opportunity any time and anywhere.