Opening a geode is like opening a present—you don’t know what you’ll find, but chances are you’re going to like it. Naturally-occurring crystals form inside geodes, ranging in color from clear and white to pink and even purple. Many are surrounded by sedimentary layers in assorted hues—and from the outside, a geode looks like nothing more than a plain old ugly rock! You break it open and find something awesome inside. That’s the fun part.

The science part comes in when a child holds a geode in his or her hand and starts wondering how it was formed. What happened in the earth millions of years ago to make something so cool? Why are crystals shaped that way? How did they get to be that color? And how did crystals get inside a rock?

Several geode kits are on the market today, and the best one to get depends on your child’s attention span, curiosity and coordination.

Safety Glasses Included

This multipack comes with two samples—enough to find out if your child has an interest in geology and the earth sciences. National Geographic

Check Price

If you’re not sure if your child will enjoy cracking open geodes, get a kit that contains only a few. If the child shows little interest, you won’t be out a chunk of change. If the child does find it fun, and wants to do more or learn more, you can go ahead with purchasing more.

Colorful Variety

Nearly a dozen samples from around the world, and will keep a kid busy for several hours. National Geographic

Check Price

Some geode kits contain a large assortment of geodes. These provide plenty of instant gratification. The child starts out with a box of rocks, but ends up with treasures they can display. Kids get a sense of accomplishment too, because they broke open the geodes themselves. Make sure you get a kit that has a learning guide included, so the child will have the opportunity to find out more about the treasures he or she just found.

Comes with Identification Guide

In addition to two stones that can be cracked open to reveal minerals, there are hundreds of other dug up treasures in this set, teaching your little one about both geology and paleontology. Dancing Bear

Check Price

Some kits provide more than just geodes—they also have various minerals and gemstones, along with fossils such as shark teeth and brachiopods. The advantage to these sets is that they provide a physical activity, along with the opportunity to find and learn more about other types of rocks and minerals—and be exposed to a bit of paleontology.