The video is being made. Until it arrives, here is what it will say (111 words, about 56 seconds):

Here's Miss Price's class at the park pond on a still morning.

Dana drops a stone in, and ripples spread out from the splash, ring after ring.

Far across the pond, a duck floats. The ripples reach it, and the duck starts to bob up and down.

But the duck does not float away: it bobs and stays right where it is. So what traveled across the pond to reach it?

To find out, we will look at what a ripple carries, how to tell one ripple from another, and how a pattern of flashes can carry a message.

Okay, so are you ready to follow the ripple across the pond?

It ends with a ready line. Then pick a reply below — any reply counts.