Weekly Science Experiment #10

This week's experiment actually started last week.  In fact, all the interesting things happened on last Friday and Saturday and today was only interesting because we got to throw the finished remains in the garbage can.  I suppose, though, that scientists spend a good deal of time disposing of their left-over cultures and samples and compounds, so we can list today's activity as a review of good laboratory practices.

Anyway, as fascinating as discussions about throwing away science projects are, what you really want to know is "What did you do?"  The answer is: We grew Eggshell Geodes.  I found this experiment on the Connections Academy website (with really nice pictures and clear explanations of the process) and it looked like fun.  Turns out it was!  

First, the kids and I talked about what geodes were and how they formed (the basics here)

(Image found here)

Second, we cleaned out some eggshells and set them up in a mini-muffin tray.

Third, we made our mixtures (check the website above for the recipes).  Blair had sugar and water and red food coloring.

Ian had baking soda, water, and green food coloring.

Brynn had table salt, water, and blue food coloring.

Fourth, we set the eggshells on the microwave and waited.  Our instructions told us we would see crystals begin to develop in about five days.

We must be extra good scientists, because ours were already growing by the next morning.

At least the blue and green ones were - the red one never did anything except turn into a sticky syrup.

 Oh well, two out of three isn't bad.

The kids made on other interesting observation: the green food coloring had mostly disappeared from the crystals by today, and the blue crystals were also fading.  Does anyone know why that would happen?