What is a gerund? (in simple terms please!)

[ReadytoOrderSir]

I teach year 4. We're going to do some work on suffixes next week. I've been merrily making lists of words and suffixes for them to experiment with. My top set are going to need a challenge though. In searching I've got myself all tied up in knots and generally confused...

What, in simple it's Sunday evening and I've done enough planning already year 4 terms, is a gerund?

I've grasped that its formed from a verb plus -ing... but is there more to it than that? Googling is not helping as I'm getting stuff too techy for my poor scientist-turned-teacher brain.

Thank you

... and I've spotted the apostrophe missing from it's in my second paragraph. Typo rather than ignorance, I promise.

It's a noun formed from a verb with 'ing' on the end, e.g. 'She didn't like my leaving so soon.'

Make sense?

Thank you Neoprene ... but this is where I struggle! Leaving is a noun? I though it was something that I did, therefore a verb?

this explains it quite simply and gives some examples you might find helpful.

Ah! I think that it's becoming clearer thanks to the link Dysgu. Thank you. Alaska is fun. Dancing is fun. Dancing is a 'thing', so a noun. Leaving is a 'thing'.

That'll do for my class. If they get beyond that I'll send them to the year 6 teacher!

Many thanks to you both.

... and I've spotted the apostrophe missing from it's in my second paragraph.

Third paragraph.

Good link, Dysgu.

I think the confusion is that 'dancing' and 'leaving', etc can be verbs or nouns - depending on the context.
Here they are verbs ('doing' words):
I am leaving in the afternoon.
I was dancing all night.

Here they are nouns (things) as gerunds:
I hope her leaving won't be painful for me.
The.best dancing can be found at Club Tropicana. ('80s child here).

Any clearer now?