To be frank, I'm not a native English speaker, but I do English at the University and we're having practice at school in a year and now we're learning how to teach.
The homework we're given is to explain -s in the Present Indefinite in 3rd person singular in a very comprehensible way; probably, to think of a short fairytale, or something that they (the children) would understand easily and never forget.
I hope that there are very experienced teachers, who can help me with it, or who can share their methods and techniques. If you can, I'd be very thankful, indeed.
Look forward to hearing from you!