Secrets of the Geodes: Sneaky STEM

Once you see it you cannot un-see it.

Marge at Tiny Tips for Library Fun detailed our great joint program, the first one of the summer. We wanted to do something about geodes, which we had housed in the porthole that month, a display area regarded with wonder by children all over the city. Wouldn't it be cool if we actually let them touch the stuff from the porthole?! The program description for PR ended with, "after the program, they'll disappear forever." I mean we decided to hold the geode program again before we send them back to the great people at UW Geology Museum but we had no way of knowing that at the time. Additionally, the day after the program the porthole was filled by other collections shared by local kids. If I wasn't planning this program I would've been totally freaked out by my librarian magic.

Anyway, I thought I'd add a bit about how I did the geode part of the library camp-out, since this became too long to be a comment on Marge's post:

 When the kids got into the room, all of geodes were already removed from the porthole and placed under blankets. I only had one out at that time, and it was with me, in front of the room. This was an important piece, setting the children up for success. You want them to listen to you, but they don't know yet that what you're going to say has value-- or if you're going to say anything at all. Hiding the geodes while I explained them (and so that they could appreciate what they were looking at more) was a good way to avoid the chaos.

Adding the trace elements

To explain the geodes, I used: two Styrofoam bowls that could be held together to look like a hollow rock
or space ship, or what have you), water in a clear cup, and food coloring. I demonstrated how water flows in and out by putting food coloring in the water (in front of the kids, to help them understand trace elements) and pouring in one of the Styrofoam bowls. Then, I poured it from that bowl to the second bowl. I held up the first bowl to show that some food coloring stayed, and asked them to imagine this happening over and over again for millions and millions of years, from the times of the dinosaurs until now. I wasn't sure if it would go over well, my little experiment, but you could hear a pin drop! I guess our geode secrets were mystifying after all.

I actually didn't get the above demonstration from anywhere; I just made it up! Feel free to use it though. Also, I see I still have my notes from that talk, so here you go:

GEODES:

--How in the world are these things made?!

                -- Geodes actually start out as hollow rocks. Somehow, a little bubble of air ends up inside it. This could be from a volcano explosion or from the remains of a tree root or animal.

The water flows in

                --The hollow space allows for water to flow in and out of it for millions of years! With the water comes whatever was in the water—minerals which, over those millions of years, build up and form crystals!

                -- Before they’re found by whoever discovers them—it could be scientists, it could be kids—these geodes look like normal rocks, but sometimes really round because if so much water has traveled through the rock, it probably also traveled over and around the rock and that smoothed the rock out; this is called erosion. It’s only when you break the rock open that you get to see the awesomeness inside!

The water flows out, leaving trace element residue

                -- Things called trace elements cause the colors. It’s kind of like food coloring: if you put food coloring in water, it will go wherever the water goes. But when the water dries up, the color stays. Trace elements work the same way, staying long after the water has dried up.

Some stories we have in the kids room claim that dragons hatched from geodes found by kids.  How cool is that?!

--As you can see, geodes are like a Tootsie Roll Pop: hard on the outside with a sweet surprise on the inside!

Afterward, I had the teen volunteers uncover the geodes with a flourish, and the kids were free to roam!

Along with the Tootsie Roll Pop giveaway at the end, families also left with a print out from this idea to make egg geodes at home. I only used the Kosher salt one for safety reasons, and only included the ingredients and directions (otherwise the handout would be 22 pages long).

Okay, now head back over to Marge's post to hear the rest of the story.
Happy geoding!