Lesson Plans > Science
& Colorful Crystals
Salt, sugar, borax, washing soda.... There is a long list of ingredients that can go into solutions which form crystals. The contributors on the T2T mailing list are seasoned pros with this one. They offer advice on success growing crystals as well as recipes and links.
You can make crystals using a variety of different things, salt, sugar, etc, but the quickest crystals are made with borax (which you can find in any supermarket). Just dissolve as much borax into quite warm water until no more will dissolve into it anymore (pieces fall down to the bottom and no matter how much you stir they won't disolve). Put a peice of string or a pipecleaner that has been formed into a shape into the solution and let it sit overnight. You will have beautiful crystals in the morning. I did this with my grade 1/2 split and they love the crystals that were formed. Sugar crystals are made the same way but take up to a week to form, but at least they are edible. -Lisa
My own kids have grown sugar crystals successfully for 3 or 4 years in a row. My daughter even did an exhibit on which materials do crystals grow on best, and she got them to grow on rubber bands, can lids, paper, buttons, plastic etc.
The key is to super saturate the water with sugar. Crystals cannot grow unless the liquid is super saturated. That means you have to boil the water and put in around 2 or 3 times the volume of sugar as water. We usually put 2 or 3 cups of sugar in 1/2 cup of boiling water. The sugar must be added while the water boils, and you continue to stir and boil until the water is "crystal" clear.
Then you immediately pour the water into a jar, punch a hole in the lid (or multiple holes in a big jar if you are growing multiple crystals. Then tie a thread around an object (best to use a rough surface rock that is clean if you plan on eating), put the other end of the string through the hole just so the rock is dangling in the middle or near the top of the water. It must be completely immersed, though.
The next item is VERY important: There can be no movement at all for about a month. The crystalizing process will not proceed well if the water is constantly - or even occassionaly - shaked. The jar must not be touched at all. You will get tons of crystals!
When my daughter compared materials, we had a very large jar and had a lot of solution. She had numerous objects dangling in the same solution so we were able to compare the various materials ability to attract crystaline growth. Good luck! There's nothing to it. -Gail
To make a salt rock garden use a sponge, porous rock, broken bits of brick, clay pots, or a combination of these. (anything that really absorbs water...) Soak these pieces in plain water until thoroughly wet. If using a sponge, squeeze out excess water. Arrange them to suit your fancy, placing some on top of others, in a glass or ceramic dish. A metal one might be ruined.
Combine 4 tablespoons each of water, ammonia, and liquid laundry bluing. Pour this solution over the wet rocks until evenly dampened. A drop or two of food coloring may be dropped on to the rocks for color. Sprinkle 4 tablespoons salt evenly over the "garden".
The idea is to cover all of the garden. But don't overdo it and have liquid standing in the dish. It will begin to grow within a few hours.
If it gets knocked down, add some of the original solution to the rocks. It will grow again on top of what is left. -Vincent
We have been studying rocks and minerals. The kids were fascinated with geodes and thunder eggs. So I found a neat experiment/craft to do. You make a "geode" in a half walnut shell. You dissolve alum (kitchen spice rack) in hot water to saturation point. Then pour it into clean walnut shells. (I had the kids make supports from play dough so they would stand straight.) You can also add food coloring. Set them where they won't jiggle or be tipped for several days. The water evaporates and leaves crystals behind coating the inside of the walnut. I hot-glued a red ribbon around the edge and hung them on our Christmas tree. They sparkle nicely. It would be fun to glue in a small piece of fools gold as well in the center of the "geode."
I used one small container of alum in about 1/2 cup of hot water for 24 walnut half-shells. It's like a 2 parts water to 1 part alum mixture. -Alice in Phoenix
I have my 2nd graders stir Borax into very hot (I bring it almost to a boil) water until it no longer dissolves. Dip objects into it and leave overnight. We made crystal stars out of pipe cleaners for Christmas and they turned out well. -Rita
The links below have more ideas and recipes as well: http://www.teelfamily.com/activities/snow/boraxsnowflake.html http://www1.islandnet.com/~yesmag/projects/projects.html http://www.ponyshow.com/kidsnet/science/crystal.htm
* What is washing soda? We've heard this question before! Elma, the very friendly representative we spoke with at Arm & Hammer, explained that washing soda is 100% sodium carbonate. You can find it in your grocer's detergent aisle in Arm & Hammer's trademark bright yellow-color box. It's about the size of a box of cereal.
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