Caves can look magical. As water drips from the ceiling, “minerals” (teeny specks of metal and rock) in the water stay behind to form crystals hanging from the ceiling (stalactites) and pointing up from the ground (stalagmites). One cave in Naica, Mexico can reach 136 degrees F, because it’s above a hot puddle of magma, the melted rock that explodes out of volcanoes. The hot water holds extra minerals, so it makes really huge see-through crystals. This hand is holding a giant one, and others are up to 39 feet long!

*Wee ones:* The crystal has triangle-shaped peaks. Try to find 3 triangle-shaped things in your room.

*Little kids:* Which is taller, a 9-foot crystal spike or a 13-foot spike? *Bonus:* If that 39-foot crystal grows 1 more foot, how long will it be?

*Big kids:* The water has been at least 122 degrees for half a million years! How much hotter than that is its 136-degree record? *Bonus:* If that giant crystal took 390,000 years to grow 39 feet, about how long did it take to grow each foot?

Answers:*Wee ones:* Items might include paper airplanes, designs on curtains or bedding, or flags.

*Little kids:* The 13-foot crystal spike. *Bonus:* 40 feet.

*Big kids:* 14 degrees. *Bonus:* 10,000 years per foot.