I don �t agree with papadeli �s reply. The difference is between the activity with its result, and the process of the activity. It �s a rather subtle difference, so you might not understand it much better after my explanation.
"Listen to your teacher giving instructions" puts the emphasis on the process (as the continuous tenses generally do), more than the result.
"Listen to your teacher give instructions" puts the emphasis on the whole lesson and its results, rather than the process during the lesson.
He helped his mother bake the cake. This emphasizes that he was there for the whole experience, and there was a cake as a result.
He helped his mother baking the cake. This implies that he wasn �t involved in the whole event, but he did provide some help at some time during the process.
The doctor watched him walk up the stairs, and was amazed at his progress. (result)
The doctor watched him walking up the stairs, and was able to diagnose his problem better after that. (process)
I sure hope this helps you, nabeera. I know you are working hard to understand the finer points of English. Some things are pretty difficult to explain.
Bruce
