Salt Dough Caves

As a last activity in exploring caves, I let the kids make salt dough caves and formations. My kids love working with salt dough. I gathered up some materials for the day including cardboard bases, salt, flour, water, and a few books on caves (note the Caves of the Desert from Saudi Arabia- Dan recently traveled there and brought home this book because it had large pictures with both English and Arabic text- he had forgotten we were doing a unit on caves- very cool)
As always when I want a homemade recipe for goop, I turn to my Kid Concoctions manual. In this case I think the recipe is too wet. So, we modified it and got things going. Making large items like caves, I thought we'd need a double batch. That calls for A LOT of salt. Just so you know.

This gave us a great chance to double a recipe and do some family "living" math. R9 got a great introduction to multiplying fractions by doing this before we made the dough.

I also took the opportunity to review how caves are made and where they are found. Limestone anyone? Right after we got married, we lived in Virginia and I worked at a school in Maryland. I was also going to graduate school. I used to drive from our condo in Virginia to the middle school I worked in and to and from graduate school- all of those rides involved traversing a large limestone deposit. Sinkholes would open up every now and then. One did open and swallow a car on the route between home and graduate school. My carpool partner is the earth science teacher at the school and every time a sink hole made the news he would say, "If one opens up on I-70 that's going to make national news!" Good ol' Garry...such a beacon of hope! One did open up near the entrance to the Genstar Quarrry outside Frederick, Maryland and we used to go by there everyday...hence my colleague's frequent comments. Comments that used to also have a shade of opinion on the quarry's responsibility in sinkholes forming. Ahem.

Anyway, I know all about limestone and water forming caves under the ground. Good times...
R9 LOVES to play with dough, paper mache or anything else that involves getting her hands dirty. The salt did irritate her hands after a while so she did complain about that.
We found the dough was still too sticky and heavy to form a good caves. I had visions of cave formations and all kinds of things. This dough was too dense. Next time..Model Magic!

Below are the finished products and the only one I can easily identify is J4's. Can you pick it out from the rest? The kids grew impatient with the medium for the task. Sometimes a project is like that. I've had a few like that myself.




We didn't have quite enough salt to do the job, but we figured it was close enough. However, I gave E11 the challenge to figure it out using the weight of the package.
But what about the conversion? E11 decided to see how much a cup of salt would weigh. Only we had no salt left...he met this challenge by deciding to try sugar instead. This made for a good conversation on molecular weight and how salt and sugar were different.
Our next stop in the world of earth science is volcanoes. Fun stuff.