Noun clause

A noun clause contains a subject and a verb.

Example
I know what he was doing there.

In the classroom
A way for learners to identify a noun clause is for them to change the noun clause for ‘it’, ‘he’ or ‘she’ and see if it still works. Noun clauses are a useful area to explore with more advanced learners, who can make their language more sophisticated by extending the complexity of noun clauses they use.

Further links:
https://www.teachingenglish.org.uk/article/noun-phrase
https://www.teachingenglish.org.uk/article/using-mind-maps-develop-writing