STEM Activity Idea: CRYSTAL SNOWFLAKE Program Level: Brownie Learn how crystals are formed, and create your own snowflake that won t melt!

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1 CRYSTAL SNOWFLAKE Learn how crystals are formed, and create your own snowflake that won t melt! - string (12 inches) - wide mouth jar - white pipe cleaner - food coloring (optional) - long spoon - tablespoon - boiling water - Borax - small wooden dowel or pencil - scissors - oven mitts or towels - paper towels 1. Show the girls how to cut their pipe cleaner into three equal sections. Have the girls twist the three sections together in the middle so the pipe cleaners look like a six-pointed star. The snowflake should fit inside the mouth of their jar easily, and if it is too big, you will need to ask them to trim the edges until the snowflake fits in smoothly. 2. Ask the girls to tie one end of their string to one of the points on their snowflake. Then ask the girls to tie the other end of their string around the middle of their dowel or pencil. 3. Adults need to pour boiling water into each jar, reminding the girls not to touch the outside of the jar or the water. 4. For each cup of water, the girls will need to add three tablespoons of Borax. This may be easier to pre-measure for each girl if the jars are not the same sizes. The girls can add the Borax one tablespoon at a time, stirring after each addition. Not all of the Borax will dissolve. 5. If the girls want to add food coloring, they may add a couple drops after the Borax is added. 6. Ask the girls to place their snowflake in the jar so the pencil or dowel rests on the edge of the jar. The snowflake should float freely, so if the string is too long the girls will need to roll the string around the pencil or dowel until the snowflake isn t touching the bottom of the jar. 7. The girls can put the jars somewhere out of the way, using towels or oven mitts if the jars are too hot to touch. The jars will need to sit overnight undisturbed. 8. The girls can remove the snowflakes from the jars the next day and let them air-dry on paper towels. Crystals are molecules arranged in repeating patterns. When you dissolve Borax crystals in hot water, the warmer water molecules move faster allowing for more Borax to dissolve. As the water cools, there isn t as much room for the Borax so crystals begin to form on top of each other, creating a crystal structure around the pipe cleaner.

2 LAVA LAMP Create your own lava lamp with a few simple materials and a little bit of science. - water - vegetable oil - antacid tablets - clear plastic bottle - food coloring - funnel (optional) 1. Let the girls fill their bottles until they are about one quarter full. Depending on your work area, a funnel might be useful to prevent spills. 2. Help the girls pour vegetable oil into the bottle until it is almost full. 3. Ask the girls to watch what happens as the oil and water separate. 4. Once the oil and water have separated, let the girls add about a dozen drops of food coloring. The girls can watch how the food coloring drops through the oil and mixes with the water. 5. Show the girls how to break an antacid tablet into five or six pieces and add them to the bottle. They can put the cap on their bottles and watch what happens. 6. When they want to lava lamp to move again, they will just need to add another antacid tablet. Oil has a lower density than water, and food coloring is primarily water. When the food coloring was put on the oil, the food coloring sank to the level with the water because they had similar densities. When you drop the antacid tablet into the bottle, they sink to the bottom because they are heavier than the oil and the water. As the tablet interacts with the water, tiny carbon dioxide bubbles form. Those bubbles rise to the top of the bottle to escape into the atmosphere, and as they rise, they take some of the colored water with them. When the carbon dioxide escapes, the water sinks back to the bottom of the bottle.

3 MARSHMALLOW TOWER Marshmallows aren t just for s mores, they can help you build a tower! Supplies: - uncooked spaghetti - measuring tape - marshmallows (variety of sizes) 1. Let the girls divide themselves into groups of two or three. Place the materials in a central location so all groups can easily access the supplies. 2. Challenge the girls to make the tallest free-standing tower they can with uncooked spaghetti and marshmallows. Lay out a couple ground rules about safety (all girls need to have their feet on the ground, no standing on chairs or tables to build) and about how many supplies they can retrieve at a time. A good starting point would be to let each group start with 10 marshmallows and 20 pieces of spaghetti. You can give each group another set of supplies every 5-10 minutes, depending on the momentum of the groups. 3. Let the groups build with little direction for a few minutes. If the groups are struggling, bring them back together to discuss what s working and what is difficult. Once the girls get a plan in place the momentum should pick up. 4. Set a time limit to do the first measurements, if you have more time, allow the girls continue until they feel like they can t build the tower any higher. 5. Once the towers have been completed, discuss the different approaches girls took when building their towers. Which groups focused on a strong base before building height? Who needed to stabilize the structure because it was built to high too fast? What were the pros and cons of the building materials? If this activity was to be done again with different materials, what would you want to try? Creative problem solving is an important part of developing a critical thinker. There is no right way to build a tower with spaghetti and marshmallows, so being pushed to try different methods and experience immediate struggles and successes are valuable opportunities for girls. Working in a small group allows for each girl to play an active part in building the tower, and each girl should have a chance to try her ideas. If the girls did the activity individually, they may feel frustrated quickly instead of approaching the problem from a variety of viewpoints. If you have time to do an activity like this again, other possible supplies could be: newspapers and masking tape, toothpicks and gumdrops, K Nex building materials, pipe cleaners, craft sticks, etc.

4 OOBLECK Is it a liquid or a solid? This is a slimy way to learn about the states of matter. Supplies: - 1 cup cornstarch per girl - water and pitcher - food coloring (optional) - disposable cups - one large mixing bowl - paper towels (clean up) 1. To make the Oobleck, pour the cornstarch into a mixing bowl. Add a couple drops of food coloring to a pitcher of water (if desired) and then slowly start pouring the water into the cornstarch. You will want to mix with your hand as you go, making sure to incorporate the dry cornstarch. If you are preparing this ahead of time, you may want to add enough water to make the mixture runny because it will start to harden if you let it sit for a few hours. You can always add more cornstarch or more water to get it to the right consistency. 2. Divide the Oobleck into cups so each girl has their own cup of Oobleck. It may be easier to pour the Oobleck into the cups rather than try to scoop it out of the bowl. You may also have to mix in a little more water at this point if the mixture isn t runny enough. 3. Let the girls explore as much as time allows you may need to restock some Oobleck cups if there is a lot of spilling. Let the girls squeeze it in their hands, and let it drop from their fingers. Have them show you how it has properties of a solid and of a liquid. 4. Clean up girls will need to rinse their hands with water, table surfaces will need to be wiped down several times with damp paper towels. 5. Have a discussion about the different properties of Oobleck: What did it feel like? What did it remind you of? How could something like this be useful? Oobleck is a non-newtonian fluid, meaning that it has properties of a liquid and properties of a solid at the same time. It is a great way to get messy and ask good questions. Dr. Seuss wrote a book, Bartholomew and the Oobleck, which can spark an interesting discussion about how Oobleck could affect the community, and how the girls would design a cleanup plan. Alternative: Let the girls make the Oobleck in small groups in mixing bowls. Each group can have a pitcher of water and a bowl of cornstarch to work with.

5 ZOOM GLUE Stuck with nothing to do? Take a few simple ingredients and make your own glue! - ½ cup skim milk - 2 tablespoons vinegar - 3 large paper cups - 5 paper towels - Rubber band - Plastic spoon - 1 teaspoon baking soda - 3 tablespoons water 1. Slowly pour the vinegar into the cup with milk. Stir together for 30 seconds to a minute until lumps start to form. The lumps are called curds, and the liquid is called whey. 2. Make a system to separate the curds from the whey. Put a folded paper towel over one of the large paper cups. Push down in the center so it forms a bowl shape. Put a rubber band around the top of the cup to hold the paper towel. 3. Pour the curds and whey into the cup with the paper towel. 4. Use a spoon to scoop the curds onto a clean paper towel. 5. Put another clean paper towel on top of the curds and gently press down. The curds should begin to feel firm and not squishy. 6. Put the curds in the last paper cup. Add 2 teaspoons of water to the curds and stir. 7. Add the baking soda and stir carefully. The bubbles mean that the baking soda and vinegar are reacting and creating carbon dioxide bubbles. 8. Continue to add a little water and stir until it is the glue consistency that you need. By mixing milk and vinegar together, the vinegar makes the protein in the milk stick together to form small lumps called curds. When you add baking soda to the curds, the leftover vinegar reacts with the baking soda. Once you add a little water to get to the right consistency, you have glue! Glue adheres to the surfaces of the materials you want to stick together and as it hardens in holds objects together. Glue can be different strengths and can be used in various ways.