Authors: Maddie Van Beek and Dr. Erin Nyren

​Merry Christmas! This is the last of our holiday science. Use some of the sweets around your house to build gingerbread houses! You can either make your own gingerbread, or you can use graham crackers for your building. Before you start building, let’s learn a little bit about building structures.


What kinds of shapes do you usually see in houses? Think about the buildings you see every day. What shapes does your house have?


You probably can find circles, squares, and triangles in any building you look at. Walk around your neighborhood and record the kinds of shapes that you see!


What’s more sturdy, a square or a triangle? Test it out. Connect three marshmallows with toothpicks to create a triangle. Next, connect three marshmallows with toothpicks to create a square. Squeeze both shapes and try to move them around... which is more sturdy? You probably noticed that the triangle kept its shape better than the square. That should help you as you think about how to build your structure!


There are four things that every building needs to be stable and provide shelter:
1. Foundation: The base of the building.
2. Floor: The part of the building we walk on.
3. Walls: Defines the building, divides the building into rooms, holds up the roof.
4. Roof: The top of the building that provides shelter for the people inside.


Below is an example of a simple house structure. See if you can build one! Try out your own ideas with the shapes you’ve seen around your neighborhood. Be creative!

Now that you’ve practiced your building, let’s make gingerbread houses!


Here’s some examples of houses that we built with graham crackers last week!

YOU WILL NEED:
* Marshmallows
* Toothpicks
* Gingerbread or graham crackers
* Royal icing (recipe below)
* Plastic baggies
* Scissors
* Paper plate or pan
* Assorted candies (licorice, chocolate candies, gum drops, and anything colorful works great!)


To make royal icing:
Using an electric mixer, combine 2 pounds (1 kilogram) of powdered sugar with 4 large pasteurized egg whites. Blend until the mixture is smooth, with no lumps of sugar. It should be stiff and sticky!


Here’s what to do!
1. Draw your building plan on paper first. It always helps to have a plan!
2. Spoon frosting into a baggie and seal it. Cut off just the tip of one corner of the bag. This will be your icing tool.
3. Break up your gingerbread or graham crackers into the shapes you want to use for your house.
4. Use a pan or paper plate for your construction area. Build your structure using your shapes for your structure and frosting for glue! If your building collapses, don’t worry! You can always try again. Sometimes it takes a few tries to find the right building technique, and it does take a while for frosting to solidify.
5. Once you build your structure, use candies to decorate your house. Have fun, and Merry Christmas!


Image and video credits, in order of appearance: 
House diagram created by Dr. Erin Nyren
Photos taken by Maddie Van Beek

Author: Maddie Van Beek 

Who doesn’t love to play with slime?! Two weeks ago, we made Peppermint Oobleck. Today, we are going to use a different type of slime recipe for some gooey Christmas fun! 


What is slime? 
The slime we are going to create today is a substance called a polymer. A polymer is a large molecule formed from lots of smaller molecules. These smaller molecules, called monomers, form a long chain. 


Poly = many
Mono = one
Mer = parts


A polymer has many parts, a monomer has one part. Thus, many monomers form a polymer! 


Let’s back up... what exactly is a polymer, anyway? A polymer is a large molecule, or macromolecule, that consists of many repeated subunits. Polymers are created by linking smaller monomers into a chain. Think of the monomers as beads, and the polymer as a necklace made by stringing the beads together. 


Where do we see polymers in our daily lives? 
Polymers appear in many products that you see all the time, such as plastic or rubber. Another common polymer is the DNA in your body! DNA is a chain present in all the cells of your body, and it’s what makes you uniquely different from everyone else! 


In our slime recipe, one of the main ingredients is glue. Glue is actually a liquid polymer. The molecules of glue are in separate little strands before you add anything to it. Once you add the special ingredient (laundry starch) to the glue, it acts as a binding agent that links all the little strands together to create a more solid polymer, or in other words... SLIME. 


What’s happening when you add liquid starch to glue? Glue is already a polymer, but it isn’t a very strong one. Cross-linking occurs when you add a binding agent to a weak polymer to make it stronger. See the image below. The once weak individual polymer strands are made sturdier because they are cross-linked by the binding agent! ​

You are going to create the same type of slime, but you’ll color half of your slime red and swirl it with the other slime to give it a candy cane look for Christmas! 


YOU WILL NEED:
(You can purchase our basic slime kit at:
http://www.discoveryexpresskids.com/store/p83/SLIME%21__A_polymer_science_kit_for_ages_5_and_up.html)

• Clear liquid school glue
• White liquid school glue
• Liquid laundry starch
• Water
• Red food coloring
• Bowls
• Measuring cups

Here’s what to do! 
1. Measure 1/4 cup of the clear craft glue and dump it into the mixing bowl. 
2. Pour 1/4 cup of water into the mixing bowl and use the spoon to stir the water into the glue until it looks smooth and well-blended. Write down your observations so far. How does adding water to the glue change it? Add about six drops of red food coloring and stir until the color is even. 
3. Add 1/4 cup of liquid starch to the mixing bowl and stir it in. How does the consistency of the glue change once you add the starch? Record your observations. 

4. Once you stir the starch in, pick up your slime and play with it! What does it feel like? Look like? Is this what you expected to happen? 

5. Repeat steps 1-4 with the white craft glue. 

6. Once you’ve created the red slime and the white slime, swirl it together for a candy cane look! Have fun! 



For more slimy fun, check out our blog from last year: http://www.discoveryexpresskids.com/blog/two-times-the-slime-fun-with-polymers

​

Image credits:
Cross-linking image created by Dr. Erin Nyren

Photos taken by Maddie Van Beek. 

Author: Maddie Van Beek

Christmas Yarn Ornaments: How does static electricity work?

Have you ever pulled a sweater over your head only to look in the mirror and find that your hair is sticking straight up?! This is caused by static electricity. Static is more prevalent in the winter time because the air is usually drier than in other seasons. 

​Less humidity = more static. More humidity = less static.

What is static? Static electricity occurs when there is an uneven balance of electric charges on the surface of a material. This uneven balance causes that material to either be attracted to something (if that something has an opposite charge) or repel from something (if that something has the same charge). For example, when you pull that fuzzy sweater over your head, it causes your hair to be negatively charged. Because your hairs are negatively charged, they repel each other--they want to be as far away from each other as possible, so they stick straight up!
​
Check out the link below for an in-depth explanation of what static electricity is. ​

10. Once you’re done covering your balloon, carefully roll it in the glue mixture and then place it on the newspaper to dry.

11. Repeat steps 9 and 10 until you are done creating as many ornaments as you want! Leave them to dry overnight.

​12. In the morning, use a pin to pop the balloons. You are left with a cool homemade yarn ornament! 

Image credits:
All images taken by Maddie Van Beek

In this experiment, you are going to create Christmas shapes out of a baking soda paste. Once the shapes dry, you’ll put them in a pan of vinegar and watch them FIZZ! Why will this happen? Baking soda, or sodium bicarbonate, is an example of a base. Other bases you might see in the real world are often in the form of cleaners, such as bleach or ammonia. Can you think of any others?
Vinegar is an example of an acid. You might already know that many fruits have acid in them. What else is acidic?​

So we know that baking soda is a base and vinegar is an acid... why do we see fizz when they meet? When acids and bases are mixed together, a REACTION occurs. That reaction produces carbon dioxide gas. The gas appears in the form of bubbles! Now that you know the science behind the reaction, let’s get started!


YOU WILL NEED:
* Baking Soda
* Christmas Cookie Cutters
* Water
* Vinegar
* Pan
* Bowl


Here’s what to do!
1. Dump 2 cups of baking soda into a bowl.
2. Add water a little bit at a time and stir until you have a thick baking soda paste.
3. If you would like to, add a few drops food coloring and stir into the paste.
4. Set the cookie cutter shapes that you would like to use on a pan.
5. Press the baking soda paste into the cookie cutter shapes.
6. Let dry undisturbed until the paste has hardened (a few hours).
7. Carefully pop your shapes out of the cookie cutters.
8. Fill the pan with vinegar and place your shapes in the pan. Watch the reaction happen! How long do you think it will take your shapes to fully dissolve? Make a prediction!
9. If you add more vinegar, does it help the shapes dissolve faster? Try it out!


Peppermint Oobleck
We’ve made Oobleck or SLIME in the past, but this time we’re going to make it Christmassy! What is Oobleck? When you mix cornflour and water, you get a non-newtonian fluid. A non-newtonian fluid behaves sometimes like a liquid and sometimes like a solid. It will behave like a liquid until you apply sudden pressure or stress, and then it will act like a solid.

For example, you could run across a pool of oobleck, but if you stood still, you would sink!

Watch this video to see non-newtonian fluid in action!