Monday, February 23, 2009

Kindergarten/1st grade Geology

Salt Crystal Garden


liquid bluing

Step 1: mix together:
4 tablespoons salt (one recipe recommended un-iodized salt.)
4 tablespoons liquid bluing (available in the laundry department of grocery stores)
4 tablespoons water
4 tablespoon ammonia

2. Pour the mixture over small pieces of porous rock, charcoal or pieces of broken clay flowerpots in a shallow glass or plastic bowl or plate. (Some recipes suggest soaking the charcoal, etc. in water for 15 minutes then placing it in the bowl with the growing solution.) Crystals will begin to grow in six hours and continue for three days, depending on the humidity, temperature, and how much airflow is present. To concentrate crystal growth on the charcoal and avoid them forming on the edge of the plate, coat the plate with Vaseline.
*Most recipes suggest sprinkling two more tablespoons of salt over the charcoal and on the first or second day to get the crystal growth off to a faster start.
3. Add more of the salt-bluing-ammonia-water mix starting on the third day to keep the crystals growing. Be careful to avoid dripping any of the new solution on the growing crystals or they will be damaged. In time the crystals may grow over the sides of the bowl.

*plastic or glass bowls can be used, crystals will not stain them and should wash off easily.
* add food coloring to therock in order to grow colored crystals!!

**although only household chemicals are used, some are toxic so this project should only be done under adult supervision.

How it works:
The porous material draws the solution up using capillary action. Water evaporates on the surface and the solid chemicals are left behind forming crystals. Because the evaporation is a fast process compared to the rate of crystallization and there are many rough spots for nucleation (places where crystal growth begins) the crystals grown are small and may look like small grains or even powder.
Because evaporation drives this project, place it where it has free air circulation, but no hard drafts or the delicate crystals may be blow over. Warm dry areas will have faster growth than cool moist areas. Avoid direct sunlight because this causes the liquid to evaporate faster than the growing structure can draw it up so the crystals form on the plate instead of where they are supposed to. A gentle breeze from a small fan set on its lowest setting can increase the speed at which the crystals grow by a factor of ten.

These crystals are very small and held together by the binding action of water, like fine mud. They are extremely fragile and a slight bump can cause them to collapse. Touch them and they smush (technical term for digital compression of soft, hydrated structures) to shapeless mush. So be sure to let the children know this so they are careful around them. Have the childrennote the growth of the crystals each day by drawing a picture of how it looks.

Rock and Roll!

A board of some sort

What to do:

The students are shown an inclined plane, made with a 2 X 6, long enough to lean against the top of a chair, reaching the floor. The students are told they will go outside and pick a rock that they think might roll down the inclined plane. Have the students predict the type of rock that they think might roll best. Write down their predictions. After the students return with their rock, each one will try thier rock. After everyone has had a turn, discuss the predictions. Circle the correct predictions. Introduce the word gravity and discuss the reason the rock moved down hill. Ask these questions "Which rocks rolled well? Which ones do not? "

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