What is the role of a noun?

In the first sentence, “jogging” is functioning as a noun because it appears before the verb (English has, generally speaking, a subject-verb-object word order) and there’s an adjectival subject complement–“fun”–after the verb, which modifies “jogging”.

You’ve misanalyzed your second sentence–the simple predicate is “is”. The infinitive “to jog” is functioning as a noun, but this case is a little trickier because it’s one of *two* subject complements. The first complement is the same adjectival one from the other sentence (“fun”), and the second is a nominal subject complement (“to jog”) that renames the subject–“it”.

The first grader would have to then ask what is a subject or what is a predicate and you would have to answer a person, place or thing or anything that can takes its place in a sentence.

noun..

noun is simply a word used to name a person, palce, things, state or quality.

nou can act as a subject, predicate and both.

a noun isn’t just a person, place or thing.

it’s more like a name for ANYTHING.