In Case I Didn't Know How...

Today at work I noticed a boy who can normally get himself zipped up and ready to go at the end of the day struggling with his zipper - so I offered to help him.
Me - Can I help you zip up your coat?
Boy - Sure, see this part here? It goes right in there.
Me - (nothing) - proceed to zip his coat
Boy - You got it!
Not sure if I said anything or not, but it was just too funny that he told me how that whole engaging the zipper thing works - in case I didn't know!