Compoun Noun: I am always confused to a CN by its '-ed' and '-ing' form

[Theresa]

Hi,
In "teaching documents" teaching is a noun not a gerund. There are many nouns formed by Verb + Ing. Some good examples are writing, speaking, reading and listening.
Dancing is one of my hobbies. "Dancing" here is a noun. (Some people consider it gerund)
He's good at dancing to the beat. "Dancing" here is a gerund.
Not all verbs can have "-ing" and "-ed" adj. The best way is to look up a verb in a dictionary to see if it has any derived adj.