How to use 'beside' and 'besides' correctly

My students often gets confused when it comes to using these two words. They are 'beside' and 'besides'.

The word 'beside' is a preposition and it means 'near'.
Let us look at two examples to see how it is used in sentences.
1 I sat beside John when I was watching the football match.
2 There is dustbin beside me.

As for 'besides', it is a preposition and adverb. When it is used as a preposition, it means 'in addition to' but when it acts as an adverb, it carries the meaning of 'in addition'.

You can make a sentence such as the one below to use it as a preposition.
Besides singing, the renowned singer composes her own songs.

To use 'besides' as an adverb, perhaps you can construct a sentence as follows.
Besides, I don't have the transport to go there at the moment.