Computer Science for Kids

9. Searching for Geodes

Standard: 2‐DA‐07: Represent data using multiple encoding schemes

“Now that you're well on your way to becoming our newest Forest Defender,” says the Guide, “you're ready to start working with endangered species and the data that they generate and consume.” She starts walking along the stream where the moss grows thickly. You follow her lead, noticing in passing that the stream trickles merrily over many round‐shaped stones. Some stones are worn and smooth, others have sharp edges, while still others have curious bumps and knobs. A particularly knobby stone with a chalky exterior catches your eye, and you pick it up. “What kind of stones are these?” you ask your Guide.

“There are many types, and it is our job as Forest Defenders to make sure they are not misplaced or stolen,” notes the Guide. You come to a bend in the creek and stop. “Each year we take inventory of the stones that gather in this bend. Most valuable are the geodes, and we guard them carefully.”

As you watch, the Guide takes the stone that you picked up, places it on a flat boulder, and taps it sharply several times with another stone. It breaks in half, revealing a stunning array of purple crystals inside. The colors shimmer and glint in the sunshine. “You see? Collectors love to come and take these beautiful geodes. They tramp through our forest and take all they can find. I suppose they crack them open and sell them. Because the stream moves the stones around, it's hard to tell how ...