Computer Science for Kids

11. The Stone Library

Standard: 2‐DA‐09: Refine computational models based on the data they have generated

Now you know exactly what kind of data to collect, so you turn back to building your inventory of the rocks in the riverbed. The Guide looks over your shoulder at your growing collection of data and nods. “You're doing an excellent job of gathering information and organizing it,” she says. “Now we know how many stones we have in this collection and which ones might be geodes.”

Suddenly, you hear a strange noise. It sounds like a choked sort of scream, and you jump to your feet, startled. From the corner of your eye, you see a large black bird that has flown to a branch hanging over the creek. It points its large beak in your direction, fixes you with a quizzical stare, and yells “Caw!”

“Watch out!” shouts the Guide, as the bird launches itself into the air and starts flying directly toward you. You both jump back, expecting an attack. Instead, the crow veers straight to the collection of rocks and lands on a boulder in the creek. Cocking its head here and there, it selects a particularly knobby spherical stone and picks it up. You watch as it then flies to a high tree branch and drops the stone onto a large, flat rock. The stone breaks neatly in half and reveals its sparkling interior—the bird just stole a geode!

A second crow flies to the stone where the geode lies and is met by the first crow, who ceremoniously gives the other bird half the geode. They look at each ...