I have a science background and was always waiting until my daughters' were at the age to participate in Science Projects.  Well, in my home town, this starts in third grade. The school provided some ideas, but not really any good details to follow.  I researched this on the web and found some good projects, but some wanted you to BUY their knowledge.  I came across a really good experiment for elementary school children that I thought I would share with you.  This is how to grow a Beautiful Salt Crystal Garden.

In a glass or plastic bowl, put some pieces of coal, porous brick or sponge (I personally like to use sponge).

Day 1.  Over the base material (i.e. the pieces of sponge), pour 2 tablespoons of water, two tablespoons of salt (table salt is fine), and two tablespoons of Ms. Stewart's Bluing (or other liquid laundry bluing product).

Day 2.  Add two more tablespoons of salt.

Day 3:  Pour into the bottom of the bowl (not directly on the sponge or base material) two tablespoons each of salt, water, and the liquid bluing product.  Then add a few drops of vegetable coloring or ink to each piece (it looks better if you use different colors).

By this time a beautiful flower-like growth should have appeared.  If all the conditions are not ideal, it may be necessary to add 2 tablespoons of household ammonia to aid the growth.  A free circulation of air is necessary, and these formations will develop better where the air is dry.

To keep it growing:  Add more salt, water and bluing product from time to time.  It will "bloom" into beautiful coral and crystals.  Try it!!!

Why does this work?

Table Salt (NaCl) dissolves in water.  This recipe for the salt crystal garden calls for a large amount of salt in the presence of a small amount of liquid.  Thus crystallization take place very quickly. 

Mrs. Stewart's Bluing (or other liquid bluing product) is a suspension of extremely small particles of blue powder.

As the water from the bluing and the clear water which is first added evaporate, two things happen.  The blue particles can no longer be supported and the excess salt cannot stay in solution.  The salt crystallization process will take place around the blue particles.  Small amounts of ammonia are added to speed up the evaporation process, if needed.

The purpose of the sponge pieces is to provide a means for capillary action to carry the liquid containing bluing and salt up from the main source of liquid.  This further speed up evaporation and causes the crystals to form over a larger area than just the rim of the bowl.

No chemical reaction takes place in this process, just dissolving and recrystallization aided by the bluing particles.  This is a safe and fun project to do with your children.

Have fun trying this out.  If you find this helpful, please rate this review.  Thanks.