present participle clause

I have been teaching for more than 26 years in my own language center, and also in senior high school classes along with Prep school classes. Much as a written form of a lesson can never illustrate the beauty of a real class, I briefly explain some issues relating to 'present participle clause'' :
Well, dear students let me show how simply we can switch our simple sentences into a complex structure through which you can express your notion more beauteously and impressively. One of these methods is to utilize present participle clause;

*Here I make use of some extracted parts of movies in which this structure has been used. This is to sow them how applicable and helpful it is in daily conversation.*

To create such a combined sentence, you need to have two sentences the subjects of which are the same while having present tenses or past tenses in both of them.
present continuous-present simple/ continuous
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past continuous-past simple/ continuous
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THEN I WRITE TWO SENTENCES ON THE BOARD ONE OF WHICH SHOULD BE IN CONTINUOUS FORM, WHILE THE OTHER ONE CAN BE IN A SIMPLE OR CONTINUOUS FORM.
For example:
Tom is reading a newspaper. He falls asleep.
(How to combine them) The subject of the sentence which has continuous tense and "am/ is or are" are both deleted and the can be replaced with "While" This connector is optional to be used when it is at the beginning of the sentences, but it is mandatory to be used when the shorted continuous sentence is located in the middle of the combined sentence OR "while" can be replaced with a "comma";

Tom is reading a newspaper. He falls asleep. --
-(While) reading a newspaper, he falls asleep.
-Tom falls asleep while reading a newspaper.
-Tom falls asleep, reading a newspaper.