Home School Life Journal

Home School Life Journal ........... Ceramics by Katie Bergenholtz
"Let us strive to make each moment beautiful."
Saint Francis DeSales

Building Lab

I am going through some of the activities we have done years ago and writing posts on how to do some of these hands-on projects to learn skills in a variety of topics. 

Starting soon I will be posting a series of posts all about building and some basic physical science concepts related to building structures. It is a collection of fun, simple hands-on activities for pre-K-8th grade. Here are the topics we'll cover...


  1. Compression, Tension and Torsion in Building Materials
  2. Shapes and Building
  3. Columns
  4. Paper Bridges and Loads
  5. Cables and Suspension Bridges
  6. Geodesic Domes: Triangles,Toothpick Structures and Dowel Designs 
  7. Towers
  8. Dams Under Pressure
  9. Building Tunnels
  10. Balconies and Awnings

Building Lab, Part V: Cables and Suspension Bridges



When thinking about building, your student might not think too much about the role of cables, however they are vital to a suspension bridge. A suspension bridge's cables and towers transmit the dead load of the bridge deck and the live load of traffic to the massive anchor blocks at each end of the bridge. The tension in the cables leading up from the bridge deck is balanced by the tension in the cables leading to the anchor blocks, as well as the compression in the towers. The anchor blocks must be massive enough to resist the tension in the cables caused by the weight of the bridge deck. 

Cable Demonstration



In order to demonstrate how cables can work to use the mechanical advantage that pulleys provide, you need some rope, a smooth stick like a broom handle or walking stick and some students.




Tie one end of a rope on a smooth stick like a broom handle or walking stick. Next, loop it around another stick and have the person holding the first stick to hold onto the remaining rope. It will look like this picture. 



Now, stand about three feet apart. You will need to let out some rope.



Once it is set up, have both people pull back on each broom, and you use the end of the rope to try to pull them together. It is hard to pull them together.


But, if you loop the rope first around the stick twice, it is so much easier to pull the two together this time.



Even your youngest student can pull heavier students or family members together.
source
Chesapeake Bay Bridge

Discuss how this design can also work with cables and bridges, converting the pulling-down force into a force that pulls up on the weight. 


Now that we have already looked at beam bridges, we want to look at suspension bridges and the differences between the two.

Students should find that adding the cables to their straw bridge and anchoring the cables on both sides significantly increases the load that the bridge can support. 
Make a model of a beam bridge by taping two straws together at one end.  At the other end, tape the straws together with a small piece of straw as a spacer, making a tall triangle out of straws. 
Make two sets of these, These are the two towers of the bridge. Tape these to chairs and then place another straw on top of the spacers to form a beam bridge. 
Next make a load tester by hanging a cup from the beam, and then take begin putting coins in the cup. It should hold a fair amount (about 15 coins) before the beam bends, dropping its load.
Next make a suspension bridge to compare how much it can hold. Tie the center of a length of thread around the middle of a new straw and place the straw between the towers. Pass each end of the thread or "cable" over a tower and down the other side. Pull the cable tight and anchor it on the table. The cup of the suspension bridge should hold many more coins (our held over 25 coins) and the bridge should be able to hold even more weight once the cup is filled. The difference in the ability of the bridges to hold weight and the importance of cables in larger bridges (with much heavier loads) should be easy for your students to see.

Building Lab, Part IV: Paper Bridges and Loads

Vocabulary

Loads create a force on a structure. 

Dead load The weight of the permanent, non-movable parts of a structure, such as the towers, cables, and roadway of a bridge.

Live load The weight of a structure's non-permanent, movable parts, contents, or "users," such as the traffic, people, and seagulls on a bridge. Environmental loads, such as wind, rain, and earthquakes, that can affect a structure temporarily are also live loads.

Activity


Have your students look around the room and make a list of as many different loads affecting the room as they can. 

List everyone's loads on the board. Next, have them decide whether each load is live or dead. Dead loads include the weight of the walls, ceiling, floor, and any permanent fixtures such as ceiling lights, wallpaper, paint, and windows. Live loads include things that are not fixed, such as furniture, people, signs and pictures hanging on the wall, plants, and wind blowing outside.

Have your students estimate the room's load, assuming the floor and walls weigh 50 lbs./sq.ft. and the ceiling weighs 30 lbs./sq. ft. Use a scale to weigh small furniture.

Building a Better Bridge

A bridge must support its own weight (the dead load) as well as the weight of anything placed on it, like the pennies (the live load). Changing the shape of a material can change the way it resists forces. Although a piece of paper seems flexible and weak, it can be folded, rolled, twisted, or otherwise altered to support quite a bit of weight. Students may accordion-pleat the paper, roll it, or cut it into strips and weave them together. The paper clips can be used to stiffen folded paper. Folding the paper helps it to resist bending forces created by the live load of the pennies on top of the bridge. The paper can be folded into the shape of an I-beam or accordion-pleated. Rolling the paper around the pennies and fastening the ends with paper clips is another possible solution. Students will probably find that the bridge can support more weight distributed along the bridge than at a single point.
Hold up a single piece of paper. Ask: How many pennies do you think a bridge made out of this paper can hold? After kids make some guesses, lay the sheet of paper flat across two books placed 20 cm (about 8 in.) apart. With the kids keeping count, place pennies on the bridge, near the middle, until the bridge fails.  Now introduce the activity challenge.

What can you do to the paper to make it stronger?


Materials

plain paper (such as photocopier paper)
5 paper clips
ruler
2 books or blocks
at least 100 counters, pennies, metal washers, or other small weights
scissors

Explain to your students that their task is to make a bridge out of one sheet of paper. The rules are that they can also use up to 5 paperclips, but nothing else. The sides of the bridge must rest on two equal materials such as books, or as in our case, two storage containers, with about 8 inches between the sides. They cannot use tape to tape down the sides. 

After thinking and discussing the problem, have your students describe how they think the bridge should be constructed in order to support its dead load plus the live load of the pennies.

Place the bridge they make across two supports that are 20 cm apart. Remember that the space below the bridge must be clear to allow boats to pass! To test your bridge, load it with pennies one at a time, until it collapses. Record how many pennies your bridge supported. As they test their bridges, suggest that they observe the bridges closely to determine where they fail.

Describe how well your bridge supported its dead load and the live load you placed on it. Was the bridge as strong as you thought it would be? Where did it fail?
Redesign your bridge and test it again, using a new sheet of paper. How does your second attempt compare? How can engineers test their plans for building a full-size bridge?
Is there a difference in the load your bridge can hold if you put the load in the center of the bridge compared to spreading it out along the bridge? Make a prediction and test it. 
Have a discussion about different types of bridges kids have seen. How long were they? How tall? What were the bridges designed to transport (e.g., trains, cars, people)? What other considerations went into designing the bridges (e.g., earthquakes, boat traffic)?  Use this opportunity to discuss that while engineers cannot build multiple full-size bridges to test their ideas, they use models and computer simulations to test and redesign structures.
(To see the results of our testing, click here.)

An Additional Project

Have your students each choose a large bridge to study. After research, have him create an advertisement for his bridge that highlights what has learned about the bridge, including its construction, its  use and anything else that is unique to this bridge.

Our 22nd Year of Homeschooling, March 2018

 March 2018

Quentin (8th grade)

Acting

Quentin's chosen career is acting, so has worked really hard this month auditioning for and getting parts in acting productions. He got a part in the ensemble for Pippin, which will be his first role that he has gotten for his singing. He will begin rehearsals for that in April.
He also will be part of a New Year's Eve First Night production in which he will sing and dance multiple roles in an ensemble and in duets, trios, quartets, etc. This will have multiple rehearsals over the next several months.
He will also be a part of a Summer Acting Camp's production of Le Miserables.
Fortunately because of his homeschool schedule is flexible, he can participate in all of this and still complete his school work.

American History
Quentin hasn't finished his game yet but wants to go on. I am deciding whether to acquiesce and go back to notebooking and writing papers or to insist that he finish the project before going on. The reason for my dilemma is because he needs work in both writing and completing work.

Bible
We finished our detailed study of Numbers and began studying Deuteronomy.  I am doing the study with him and I find it interesting that the parts I find the least interesting, he finds the most interesting and vice versa.

Biology
We are studying the structure of the cell. We have done various projects on this in the past but we are doing into more detail. It is helpful that we have Katie's Biology 101 college text to let us know in how much detail we should go to be seamless going from our studies to college work.


Physical Science
We have just finished our studies of water. It is such an amazing substance. We studied it's composition, it's polarity, it's solvent qualities, hydrogen bonding, cohesion and the difference between hard and soft water. In April we will be studying the hydrosphere.

English
We are still working on different types of papers, and in the process we work on many other skills such as grammar and vocabulary.

Middle School Math
He is working with fractions with Sam on the weekends. Because it is only two days a week, he won't finish his math program before the school year is over.  He and Sam have agreed that they will work on math throughout the summer, so he should be ready to go with next year's materials by September.


Voice

Quentin has been working hard with his voice lessons. In addition to preparing for the voice audition pieces for the plays he has been auditioning for, he is working on two more complex pieces from the musical Chess, Anthem and Where I Want to Be (if you listen to this video, the part in which Quentin in working on begins 2:50 into the video), which are really testing his skills.


James (10th grade)

American History II

In history we covered the following topics: America’s expanding borders; John Mashall; The Alamo; Davy Crocket; Sam Houston; Texas Independence; California Gold; Mormon migrations westward; Relocation of natives; Underground Railroad; Women’s Suffrage; Lucretia Mott; Elizabeth Stanton; Federalism; Eli Whitney’s cotton gin; Inventors and Inventions; Cable cars; Charles Goodyear’s rubber tires; Missionaries and preachers; The YMCA; Telegraph and Morse Code; Wild Bill Cody and Annie Oaklie.


World Geography

We are studying Europe in our geography studies including European culture, Scandinavia, Russia, Vatican City, Norwegian coastline, Mediterranean coast, Matterhorn, Caucasus Mountains, Apennine Mountains, Himalayas, Andes, Pyrenees Mountains, Greek Peninsula, Volga, Caspian Sea, English Channel, Mediterranean Sea, Danube, and the Ural River.


Integrated Physics and Chemistry II

We have gone in an interesting direction in our science studies and have lookef at keeping time, calendar, sundials, hourglasses, clocks, navigation, sound, frequency, pitch, sound recording, Doppler shift, earthquake waves, radio, amplifying signals, semiconductors, transistors, and parallel circuits.


English 10: Composition Skills

We have been working on spelling and pronunciation, short and long vowel sounds, vowels and consonants, blends, suffixes, prefixes, subordinate clauses, Latin roots, contractions, and borrowed words.


Basic Math Skills

We are working on geometry skills,zero studying shapes—triangles, polygons, rectangles and circles; Pythagoras, complements and supplements, transverse angles, solids, surface area, volumes, equations of one unknown, lengths and combining.


Katie and Sam, the college kids

Studying is always better with a dog to pet.
Sam and Katie seem to be doing well this semester, but were really ready for their spring break! They also got a couple of days off for snow closings.
I just happened to come across this test and I thought the professor's comment was wonderful!


Katie keeps bringing home beautiful pieces that she makes in her Ceramics II class. I was particularly taken with this piece which are fired with crystals in them, which form these violet flower shapes.
She has also entered her Birch Bark vase in a contest.

Alex (23, special needs graduate)


Alex has been busy with routine doctor's appointments. I took this photo of him at one of them because I thought the backdrop in the office was so interesting looking.

Building Lab, part 3: Columns and Arches


What role does the column take in architecture and building? Columns are often used to hold up heavy loads such as the roofs of buildings, which pushes on the column, putting it in compression. Therefore, a good column, then has to be very strong in compression.

Can a toilet paper tube then support your weight? 

Tell your students that you are going to have them place an empty dishpan, tray, or box lid on the floor, and then they are to stand an empty toilet-paper tube (the column) on one end in the pan. While holding on to the back of the chair with both hands, they will gradually press straight down on the top of the column with one foot. Have them predict whether a toilet-paper tube can withstand the compression caused by their weight. Have them explain the reason for their prediction.
Note: If your students are very young (and light) they may be able to stand on the toilet paper tube without collapsing it. This is because the tube is round and is able to distribute the compression all around evenly. If this happens to you, have an older, heavier student test it, and then you, the teacher could also test it. 
Once you do have a collapsed tube, have your students observe it to see where it failed. Have your students now brainstorm ways in which they could make the column stronger, using only tape and sand? Repeat standing on the column, using the second toilet-paper tube and your new design.

How did the strength of the two columns compare? Have your students think about why the results of the two were different. Next, tape the ends of the tube and fill it with sand. The tube now can distribute the compression of the weight outward from each sand grain and can now hold the weight, not only of your heaviest student but of an adult as well without collapsing. Wonder how much weight it would hold before it collapsed?

What can this experiment tell us about the best building materials?

For Older Students


Use the tubes to discuss circumference, diameter, and area of circles. Ask students to predict which can support a greater weight: a single column with a circumference of 24 cm or three columns with circumferences of 8 cm each? Have them test their predictions. Students will probably find that the answer depends on how they arrange the columns. Three smaller columns arranged a small distance apart in a triangular shape may support more weight than a single large central column.


Arches



An arch is a curved structure that converts the downward compression force of its own weight, and of any weight pressing down on top of it, into a force along its curve. This results in an outward and downward force along the sides and base of the arch. 

A buttress is a side support that counteracts an outward pushing force, the way bookends keep books on a shelf from sliding sideways. Buttresses are often used to support the sides of arches and tall cathedral walls, where they counteract the outward thrust.

Have two students form an arch by placing their palms together and leaning toward each other, sliding their feet as far back as they can. Caution them not to lose their balance. Ask the students where they feel a push or a pull. Next have a third student gently pull down on the top of the arch to test its strength. They should find it not too difficult to break the arch.
Now guide them to the idea of adding buttresses by asking additional students to reinforce the legs and feet of the arch-makers. Ask the how stable their legs feel now. They should see a large difference in their ability to resist the pull at the top of the arch now.

Snapshot Summary: March 2018

March 2018
March was an interesting month. The last day of winter was rainy and warm...
and on the first day of spring, it snowed.

James enjoyed some game days at his MTG club. Sam even joined him one time on his spring break.
I have been enjoying painting in my acrylics journal.

On a sad note, Katie's favorite cat, Lewis passed away.
Lewis with his brother, Clark, as kittens.
She had raised him from a tiny kitten, and his passing was very hard on Katie.

Saint Patrick's Day

 We celebrated Saint Patrick's day with friends over for corned beef and potato pasties...

 and shamrock shakes.

We also played a little poker.

Birthday

We celebrated Steven's birthday.
Katie gave him this candle-holder she made.

Building Lab, part 2: Shapes and Building



These investigations are designed so that the students can answer the question which shape is more stable, a triangle or a square.

Building with Straws

Activities and photos from 6/23/08.
Begin by building shapes using straws and paper clips. To connect two straws, slip the wide end of a paper clip into the end of one straw. Hook a second paper clip to the first. Now insert the wide end of the second clip into a second straw.

Compare the stability of the shapes. Stand each shape up and press down on the top corner. What happens? How much does each one bend and twist? How hard can you press down on each shape before it collapses?


When compression force is applied to the joints, a triangle changes shape less than a square, because the compression in the two sides is balanced by the tension in the crosspiece at the bottom, which pulls the sides together, making it a more stable shape  When compression is applied to a square, the joints rotate easily, and the shape changes.


Other Investigations


Can you reinforce the less stable shape by adding straws and paper clips?

Build the most stable structure you can using straws and paper clips. How much weight can your structure support?

Building with Toothpicks and Gum Drops

Activities and photos from 6/23/08.
Triangles make structures more stable because they formed a truss, which is a skeleton-like structure composed of struts, some of which are in compression and some in tension, which are joined to form a series of triangles.
Activities and photos from 6/23/08.
Have your students begin by building a bridge with trusses by constructed a rectangular box of toothpicks and gumdrops. Next, test its stability by pressing down on it and wiggling it and your students should find that it is not so stable.
Activities and photos from 6/23/08.

Next challenge them to add more materials to strengthen the box, by adding cross-pieces and triangular braces. Then have them extend their trusses to see how wide a gap they can make that is still stable.

Activities and photos from 6/23/08.

Shape Walk

source
Bollman Truss Bridge, spanning Little Patuxent River near Savage Mill in Savage, MD.
Take a walk with a camera and scavenger hunt looking for examples of shapes used in structures. Scaffolding cross-braces and trusses under bridges and railroad overpasses are good places to see triangles.