Teaching kids English

I'm helping some friends lead a summer school in English.
It will only consist of 5-6 classes.

What's the best way of having an introductory lecture?

They're all younger than 14 and they know almost nothing about English.

What do you recommend? A test, some games, etc...

They're just kids. I'm from Croatia, they come from random backgrounds and they know very little English, that's why they go to a summer school to get introduced.

Some of them are aged 5-7 and know practically nothing.

Others have watched TV, been on facebook and are generally more introduced to English--they can pronounce dog, cat, book and such, but they can't differentiate present simple from present continuous. None of them are connected, I just need advice on how to conduct an introductory lecture.

Any word games, crosswords, naming stuff in English and Croatian.

Have you had any experience when studying as a child?
What do you remember?

What does Cambridge do when faced with novice learners?