Back when we were in a flurry of activity (ha, do you see what I did there?) preparing for Hosanna’s Do You Wanna Build a Snowman party, the older kids became obsessed with snow and snowflakes and basically anything white and cold and fun. We rarely get any real snow around here; so we settled for cutting out paper snowflakes, spraying fake snow in our windows, and building snowmen with homemade magic snow (link here to awesome recipe). One day, when everyone was going stir crazy and I was desperately trying to think of a fun but educational activity to do, I remembered a crystal growing project I had done with my General Science class at home school co-op. I figured that we could take out the typical string and use something else to make it into a snowflake. The results ended up being quite sparkly, perfect for our snow obsession as well as a little lesson on crystals. Here’s how to make crystal snowflakes and learn a little about crystals at the same time.
If you google “growing crystals,” most sites will give you a formula using borax. Borax is great and is pretty sturdy; but alas, I did not have borax when we commenced this experiment. I decided to use alum instead. Alum makes beautiful crystals that are much more fragile and will not last a long time; however, they grow very quickly and you will see results within hours. When you purchase your alum, make sure it has potassium in it or crystals will not grow. I got mine in the spice section of the grocery store. (In case your kids ask you what alum is, its official name is potassium alum, and it is used for pickling and other household activities. It is also found in your can of baking powder, unless you buy the fancy expensive kind in the natural foods section labeled “without alum.”)
For this experiment, you will need: alum, a white pipe cleaner, a drinking glass or mason jar, a pencil, another pipe cleaner (any color), fishing line or thread, scissors, and water (You also need a small pan and access to a stove.)
First, prepare your materials. Cut the white pipe cleaner into three pieces of equal length and then twist them together in an asterisk shape. * Tie a piece of fishing line or thread to one of the points on your “snowflake”.
Now, make your solution. Put enough water to fill your glass or jar into a small pan and heat it to boiling on the stove. When the water is boiling, remove the pan from the burner and wait for the boiling to stop. As soon as the boiling stops, start adding alum to the water and stirring with a heat-resistant spoon. Keep adding alum until it will no longer dissolve. (This is evident when the water is cloudy and will not clear up.) Allow the solution to sit in the pan for a few minutes until it is again clear and any extra alum has settled to the bottom of the pan.
Next, set up the experiment. Carefully pour the solution into your glass or jar until it is high enough for your snowflake to fit. We used a juice glass and filled ours about three-fourths. If you can, try not to pour the alum that has settled in the bottom of the pan into your glass. This is called decanting, or separating a mixture into liquids and sediment. As you can see in the photo, we were not terribly successful in our decanting. Then take your pipe cleaner snowflake and dangle it in the solution. It is very important that the points of the snowflake do not touch the sides or the bottom of the glass. When you have it at the right place, tie it to the pencil and reinforce it by wrapping it with the other pipe cleaner as shown in the picture.
Be sure to put your set-up in a safe place out of the way. We set ours back on the kitchen counter where they couldn’t be disturbed for several hours. (Also, we have a certain three-year-old around here who loves to stir things up and add things as she “cooks” so….) As you can see, each child had his own snowflake to grow. We have a color system in our house that makes life so much easier. Gabi’s color is green, David’s is blue, Mikey’s is orange, and Hosanna’s is purple. That means Gabi drinks out of the green cup, uses a green plate, has a green bin for her shoes, etc. It makes it a breeze for me to know who left their cup in the living room again, and most importantly, there is no arguing.
Anyway, I digress. Call it a free tip. So let your experiment sit for several hours, checking on it from time to time by looking through the glass, NOT by touching it. After several hours have passed, or the next day as I like to call it, carefully use your pencil to lift the snowflake out of the solution and lay it gently on a clean surface. Remember that the alum crystals are very fragile and have a tendency to get knocked off easily.
This is when you get to do the observation of the snowflake. Have the kids touch it and feel the various shapes that make up the crystals. Look at the crystals with a magnifying glass. See if they can find a repeating shape or pattern in the snowflake. Gently tap one point of the snowflake with a pencil to knock off some crystals and examine those crystals more closely. What do they look like? Are they symmetrical? Then you can teach the kids some facts about crystals.
Facts about Crystals: Going Beyond the Fact that They are Super Sparkly and Very Fun to Look At
1. What is a crystal? It is a mineral that is made up of molecules that form a repeating pattern. These molecules band together to form a shape that is then repeated over and over again. Take out a crystal of sugar and look at it under a magnifying glass. Do you see that it is shaped almost like a football? Now look at a crystal of salt. You should see that it is shaped like a cube. What shape did you find in your snowflake?
In this picture, you can see points that look like pyramids. Alum crystals actually have an octahedron shape (two pyramids stacked on top of each other). There were actually dozens of nearly-perfect octahedrons on our snowflake the second time we did the experiment, and they were all visible without a magnifying glass. When studying crystals, you will find hexagons, tetragons, and other shapes as well.
2. Where do crystals come from? Crystals form in two different ways. The first is by evaporation of water from a mixture. This is what we did in our experiment. As the water evaporated, the alum powder formed into tiny crystals. The second way is by cooling of a liquid as it starts to harden. Expensive crystals like diamonds are formed when magma hardens slowly over time. Maybe you have seen rubies, emeralds, and amethysts. These are all crystals that have formed in nature by evaporation or cooling. Of course, snowflake are ice crystals that form when water cools very quickly in the atmosphere.
3. Why do crystals have sharp edges and angles? Crystals have symmetry. Symmetry is just a big fancy word that means “the same all around.” There are a few different kinds of symmetry that you can find in crystals. The first is called rotational symmetry. Basically it means that when you spin the crystal around, it is the same from all sides. Think of a ferris wheel. Every time you spin it, it looks exactly the same. The second kind of symmetry is reflection symmetry. In this case, one half of the crystal is a mirror image of the other. Think of a butterfly and how the wings look like a reflection of each other. The third kind of symmetry is inversion symmetry. Imagine that you can put a straight line through the center of the crystal and then spin the crystal around that line as if it were an axis. This is what you see in our experiment. It is very similar to a toy top.
Want to know more? Learn what the terms cleavage, isometric, and monoclinic mean, and find out what crystals are used for in the videos below.
And if you want to watch a snowflake form its crystals in time lapse, check out this link! It is very mesmerizing and illustrates all the principles of crystals we have learned.