Author: Maddie Van Beek


At one point in your life, you have crossed a bridge. Think about the different bridges you have crossed. Were they arched? Flat? Did they have cables running through them? Were there pillars on both ends or beneath the bridge? While there are many visual and structural varieties, all bridges span a distance to get you from point a to point b. There are five main categories of bridges.


Today, you are going to be an architect! An architect is someone who designs buildings and structures so they are steadily built.  Before you start building, you need to know a little more about the different types of bridges. 

 

Bridge Types

1.  Beam: The beam bridge is the simplest type of bridge. This bridge is stiff, straight, and generally short with two piers or abutments on either end. The beam bridge spans, at most, 250 feet. 

2. Arch Bridge: Just as the name suggests, this bridge is arched. Similar to the beam bridge, this bridge has two piers or abutments. The curved design allows stress to be distributed along the arch to either end. This design can span up to about 800 feet. ​

4. Cable Stayed: This bridge, like the suspension bridge, is supported with steel cables. The cables run from the road to a tower, forming an A. The cables are taught and run parallel to one another. The cable stayed design is popular for mid-length bridges, not far over 3,000 feet. ​

Use the following bridge diagrams as a reference: 

YOU WILL NEED:

•   Paper/Pencil

•   42 Gum Drops

•   7 Red

•   10 Green

•   8 Yellow

•   9 Orange

•   6 Purple

•   2 White 

•   One bag of toothpicks 

 

Here's what to do!

1.  Partner up with one to three others. 

2.  Assign a runner to get supplies, a time-keeper, and a group leader. 

3.  Design your bridge. Before you start building, you need to plan. You should be able to answer these kinds of questions: 

            a.What kind of bridge will you design? 

            b. Will you rely on one type of bridge, or will you combine two types for a more elaborate design? 

            c. What criteria are you basing your decisions on? Attractiveness? Strength? 

            d. How far will your bridge span? How high do you want your bridge to be? 

4. Use your gumdrops and toothpicks to build a bridge based off of one of the five bridge types. Use your drawing to guide you. 

            a. Once you are finished building, you will be judged based on strength and appearance. 

6.  For the last ten minutes, try building your bridge in silence. All team members must continue to participate. 

7.  Stack pennies on your bridge to see how many it will hold! Have a contest to see who has the strongest bridge. 

 

Follow-up Questions:

• How well did you work together as a group?
  
• How much harder was it when you couldn’t talk?
  
• Do you feel like everyone was included in your group?

​
Image Credits:

​Image 1: Jones, D.W. (2006). Steam across Iowa river. Retrieved from https://upload.wikimedia.org/wikipedia/commons/thumb/1/10/SteamAcrossIowaRiver.JPG/240px-SteamAcrossIowaRiver.JPG

​Image 2: Bulwersator. (2004). Double arch stone bridge, Japan. Retrieved from https://en.wikipedia.org/wiki/Arch_bridge#/media/File:NagasakiMeganebashi.jpg

Image 3: Unknown photographer. (1890). Postcard of Benjamin Baker's human cantilever bridge model. Retrieved from https://en.wikipedia.org/wiki/Cantilever_bridge#/media/File:Cantilever_bridge_human_model.jpg

​Image 4: Bayakov. (2013). "Russian bridge" in Vladivostok. Retrieved from ​https://upload.wikimedia.org/wikipedia/commons/thumb/e/eb/%22Russian_bridge%22_in_Vladivostok.jpg/1280px-%22Russian_bridge%22_in_Vladivostok.jpg

Image 5: Underhill, I. (1909). Manhattan bridge construction 1909. Retrieved from https://upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Manhattan_Bridge_Construction_1909.jpg/800px-Manhattan_Bridge_Construction_1909.jpg


References:

List of bridge types. (2016). Wikipedia. Retrieved from https://en.wikipedia.org/wiki/List_of_bridge_types

Author: Maddie Van Beek

It has been a HUMID week in Fargo, North Dakota! What does humidity mean? Humidity is the amount of moisture that is in the air. When it's humid out, it makes a hot day feel even hotter. Have you ever gotten out of a hot shower and seen steam on your mirror? It sure feels muggy if you have the door closed without the fan running! Why is it that humid air makes it feel warmer?



Test it out:



1. Stand in your bathroom with the door closed. Bring a thermometer in and check the temperature.

2. Turn the shower on hot and leave the thermometer in the bathroom. Shut the door and leave the bathroom for about three minutes.

3. Come back and check it out. What do you notice about the mirror? Does the air feel different? Check the thermometer for any temperature changes.



You probably noticed that the bathroom felt much warmer after the hot shower had been running for a while!



Option 1: Analyze the weather



YOU WILL NEED:

• Internet to check weather. 
  

1. Check the weather each day for two weeks. Record the high, the low, the humidity, and the "feels like."

2. Analyze your results.

Questions to think about: 

* Was the humidity typically higher on hotter days or cooler days?

* Did the humidity affect the "feels like" temperature?

* Did the humidity have a larger affect on hotter days or cooler days? 



Option 2: Create your own psychrometer



How do you measure humidity? In this activity, you get to create your own humidity-measuring tool called a psychrometer. Another name for the psychrometer is a wet and dry bulb thermometer. This is because a psychrometer is made of two thermometers: one with wet material wrapped around the bulb and the other with the bulb kept dry. See the picture below for reference. 

In warm weather, the water in the material keeping the bulb moist will evaporate. This evaporation will cause the bulb to cool slightly. Think of when you get out of the shower or the pool--you were warm when you went in, but as the water dries off your skin, you might get a little chilly! Because of this cooling effect from the evaporation, the wet bulb will actually have a lower temperature than the dry bulb. Let’s test it out!



YOU WILL NEED:

* Two identical thermometers

* Gauze or cotton balls

* Water

* Rubber band

* Board or sturdy piece of cardboard

* Tape 

* Thick string or wire


Here's what to do!

1. Place both thermometers outside right next to each other for 15 minutes. Check to make sure that they both say the same temperature. This will ensure that they both work identically. 

2. Wrap gauze or cotton balls around the bulb of one of the thermometers and secure it with the rubber band. Dip the gauze-wrapped bulb in water. 

3. Tape both thermometers to a sturdy piece of cardboard. They should be parallel to each other with both bulbs hanging off the end of the board. Make sure they are very secure!

4. Punch a hole in the end of the cardboard opposite the bulbs. Tie a string through the hole, about a foot long. Make sure the string is tightly knotted. 

5. Now for the fun part! Go outside in an open space and START SWINGING! Hold on tight to the string and swing the psychrometer around for 2 minutes. The swinging will help the water surrounding the wet bulb evaporate quickly. 

6. Stop swinging every 30 seconds and check the temperatures. Eventually, the wet bulb temperature will quit lowering and level off. Once the wet bulb temperature has leveled off, record the temperature for the both the dry bulb and the wet bulb. 

7. Now to find the relative humidity, you subtract the wet bulb temperature from the dry bulb temperature.

Example: 

Dry bulb = 22 degrees Celsius 
Wet Bulb = 17 degrees Celsius
22 - 17 = 5
Temperature difference = 5



8. Now that you have the difference, you consult the psychometric chart to find the relative humidity. The video below contains the psychometric chart and provides an example of how to calculate relative humidity based on your findings. 

9. Use your new psychrometer to track the relative humidity throughout the summer! 



References: 

http://www.sciencebuddies.org/science-fair-projects/project_ideas/Weather_p017.shtml#summary

http://www.livescience.com/40663-measuring-relative-humidity-science-fair-projects.html

https://en.wikipedia.org/wiki/Hygrometer#Psychrometers

https://en.wikipedia.org/wiki/Humidity



Image and Video Credits, in order of appearance:

Draper, John William. 1861. Psychrometer, “A textbook on chemistry”.  Uploaded from Wikimedia Commons on 6/19/2016. https://commons.wikimedia.org/wiki/File:Psychrometer1861.png.  Public Domain Image.

Rafalik, Christopher.  “Calculating Relative Humidity using Sling Psychrometer” Published 11/15/2013. Accessed 6/19/2016.  https://www.youtube.com/watch?v=14Q3-VtVDAI.

Author: Maddie Van Beek

​Have you ever wondered how glass is made? Glass can form naturally over time or it may be man-made. Most of the glass you see every day is man-made, but all glass has the same main ingredient--sand! The sand must be heated to extremely high temperatures in order to melt, and that melted sand changes from opaque to transparent as it cools.


Below is a picture of volcanic glass. This glass was formed from sand that was rapidly heated in a volcano and then cooled.

While naturally occurring glass is formed by sand that has been heated to an extremely high temperature, man-made glass contains other added ingredients such as sodium carbonate and calcium carbonate that make the sand melt at a lower temperature. Without these ingredients, we would have to use a lot more energy to create glass!


Check out this video to watch how glass is made:

We aren’t going to make real glass today, but we are going to use the same concepts to make sugar glass!


How are we going to do this? When you add sugar to water and stir, the sugar dissolves and creates a sugar solution. You may have experienced this if you’ve ever made Kool-Aid--the powder disappears into the water and seems to become one with the liquid. If you mix water and sugar together but then leave the sugar solution alone until the water evaporates, sugar that was once dissolved will remain! Adding a few simple ingredients in this activity (corn syrup and cream of tartar) prevents the solution from crystallizing back into sugar and leaves you with a transparent solid--sugar glass!

YOU WILL NEED:
* Granulated sugar
* Cream of Tartar (you can find this in the spice section of any grocery store)
* Water
* Light corn syrup
* Measuring cups/spoons
* Cookie sheet
* Saucepan
* Stove
* Candy thermometer
* Stirring spoon
* Non-stick cooking spray
* Food coloring
* Fork or toothpick


Here’s what to do!
1. Use measuring cups and spoons to measure out 1 3/4 cup granulated sugar, 1 cup water, 1/2 cup light corn syrup, and 1/8 teaspoon cream of tartar.
2. Combine all ingredients in a saucepan.
3. Spray your cookie sheet with non-stick cooking spray and set it off to the side.
4. Turn the burner on low/medium in order to heat your ingredients slowly. If the solution gets too hot, it will caramelize and turn a yellowish color. Stir constantly as the solution heats up.
5. Once your solution turns clear, you can stop stirring and place the candy thermometer in the saucepan. The solution will begin to boil slowly, but that’s okay. Just make sure not to get splashed!
6. Keep a close eye on the thermometer and remove the saucepan from the burner once the solution reaches the hard crack stage (between 300 and 310 degrees Fahrenheit).
7. Carefully pour the solution into the cookie sheet.
8. Now let your creativity shine! Sprinkle your choice of food coloring onto the cookie sheet of syrup. Next, use a fork or toothpick to swirl the dots of color throughout the syrup. Have fun with it! Just BE CAREFUL to not touch the hot syrup!
9. Leave the cookie sheet in a safe place to cool down. Check back a few hours later and remove your sugary, beautiful creation!


For more science activities that involve crystallization, check out:
* http://www.discoveryexpresskids.com/blog/sedimentation-and-crystallization-how-to-make-egg-geodes
* http://www.discoveryexpresskids.com/blog/sweet-solutions-rock-candy


For more science activities involving baking/cooking, check out:
* http://www.discoveryexpresskids.com/blog/science-of-baking-whats-the-difference-between-baking-soda-and-baking-powder
* http://www.discoveryexpresskids.com/blog/the-science-of-meat-tenderizer


References:
* http://www.instructables.com/id/How-to-make-Sugar-Glass/
* http://science.howstuffworks.com/innovation/28024-some-assembly-required-how-glass-is-made-video.htm
* http://www.explainthatstuff.com/glass.html
* http://www.stevespanglerscience.com/lab/experiments/stained-glass-sugar/

Author: Maddie Van Beek

With all this warm weather coming up, there’s bound to be a few water balloon fights! When you break out the water balloons, learn some science while you’re at it! Today we are going to figure out whether water balloons sink or float.


Before we start testing, let’s talk a little bit about density. We learned about liquid density when we made liquid rainbows in a jar. In this activity, we found that you can actually layer liquids because some are denser than others.


If you missed it, check it out HERE. 


As a reminder, the equation for density is:

The density equation shows us that density is mass (weight) divided by volume (the amount of space that a substance occupies).


What exactly does this mean? If one substance weighs more than another substance of the same volume, then the first substance is more dense. For example, think about 1 cup of water and 1 cup of air. Which weighs more? Clearly, water must be more dense.


What about the same substances at different temperatures? When we learned about air masses we used warm water and cold water to create a demonstration of what happens when two air masses collide. Take a look at this other cool density science experiment to find out why temperature affects water’s density:

As you saw in the video, warm water was less dense than cold water. Because of this difference in density, the warm water rose while the cold water sank.


Now that you know more about density, on to the activity!


YOU WILL NEED:
* Water balloons
* Large saucepan of water
* Hose or faucet
* Stove


Here’s what to do!
1. Fill a large saucepan with cold water.
2. Drop an empty balloon into the water. Does it sink or float? What does this tell you about balloon rubber?
3. Fill one balloon with air. Predict whether the balloon will sink or float. Think back to what you learned about density.
4. Fill a blue balloon with cold water and a red balloon with warm water. Do you think temperature will affect whether the balloons float or sink? Why or why not?
5. Drop the balloons into the saucepan of cold water. What happens? Record your results.
6. You should have noticed that both balloons still floated. Why do you think this is?
7. Remove the balloons. Now, you are going to heat the water in the saucepan. Turn the stovetop on and leave the saucepan on the burner until the water is very warm, but not boiling. Remove the saucepan from the stove.
8. Once again, fill a blue balloon with cold water and a red balloon with warm water. Drop both balloons in the saucepan of hot water. What happens this time?
9. You should have noticed that the blue balloon sank! Why is this? Think back to the demonstration about water density and temperature.
10. Wait until the water cools off and check back on the balloons. Are they sinking or floating? Why do you think this is?


Extension #1: Test other objects’ densities by dropping them in the water to see if they sink or float!


Extension #2: What would happen if you froze one of the water balloons? Try it with both the cold water and hot water. What do you observe?


Wonder why? Check out this explanation:
http://www.discoveryexpresskids.com/your-questions-answered/you-asked-dr-e-answered-here-are-the-answers-to-the-questions-you-sent-in


References:
http://www.science-sparks.com/2013/05/14/water-balloons/
http://www.discoveryexpresskids.com/blog/the-science-of-air-masses-what-happens-when-air-masses-collide
http://www.discoveryexpresskids.com/blog/rainbow-in-a-jar-learning-about-liquid-density