The video is being made. Until it arrives, here is what it will say (119 words, about 60 seconds):

Here's a river at dusk. A bat swoops over the water, a fish jumps, a frog sits on the bank, a heron stands still, and a snake slides by.

Five animals, and every one has a backbone.

Now, the bat flies like a bird, but it isn't a bird. The frog swims like the fish, but it isn't a fish.

So what is the bat, and what is the frog?

Scientists put these five into five different groups, and it isn't about who flies or swims. So what's the giveaway?

To find out, we will look at the five groups of backboned animals, and which group each animal belongs in.

Okay, so are you ready to sort the animals?

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