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.

Building Lab, Part I: Compression, Tension and Torsion in Building Materials

In order for students to understand how to choose the best building materials for the project they choose to build, students must understand how physical science comes into play. Forces act on building materials in many ways, and to help students learn about this, they can perform hands-on tests on basic building materials that can be found around the house, and then apply what they have learned to analyzing actual building structures. But first they must first learn some vocabulary words.

Compression (Squeezing)

Compression is a force that squeezes a material together, which tends to make the material become shorter. The lower columns of a skyscraper, for example, are compressed by the heavy weight above them.

Tension (Stretching)

Tension is a force that stretches a material apart which tends to make the material become longer. For example, the cables in a suspension bridge have the weight of the roadway and all the cars traveling on it pulling on them, creating tension on the cables.

Bending

When a straight material becomes curved, one side squeezes together and the other side stretches apart. This action is called bending. The top side of the metal bar is pulled apart in tension, and the bottom side is squeezed together in compression. This combination of opposite forces produces an action called bending.

Shear (Sliding)

Shear is a force that causes parts of a material to slide past one another in opposite directions. For example, during an earthquake, parts of a roadway can shear or slide in opposite directions.

Torsion (Twisting)

Torsion is an action that twists a material. For example, a bridge can twist violently in strong winds and collapse. The twisting force is called torsion. 

Builders Need to Know Their Materials

Different materials have varying abilities to withstand compression, tension, and torsion. Students can get a chance to test materials around the house to learn about these terms and about the building materials. Send your students on a scavenger hunt to find building materials such as yarn, popsicle sticks, pipe cleaners, clay, sponges, erasers, rubber bands, paper-towel tubes, pencils, cardboard, aluminum foil, drinking straws, tiles, or cloth.

Testing the Materials

Students can perform three tests on the materials gathered to determine the tension, compression and torsion abilities of each of the samples. 

Tension: To test the material in tension, pull on it or tug it from both ends.

Compression: To test the material in compression, push it together from both ends.

Torsion: To test the material in torsion, twist the two ends in different directions.

Demonstrate how to test the materials by choosing one and tug, push and twist on the sample to test tension, compression and torsion. For example, using a rope to demonstrate the tests, have two kids tug on the ends of a rope (tension), then push the ends together (compression), and finally twist the ends of the rope (torsion). They should find that the rope is strong in tension but weak in compression and torsion.

Now have each student pick a few items from what they have gathered and predict which ones will be strongest in tension, which in compression and which in torsion.

Now, have them test the materials by performing the same tests which you had demonstrated on them. Students will have to help each other in pairs to accomplish this. Then they should record their findings, ranking the materials from 1-4 (1 Very weak! It crumples or breaks with hardly any force. 2 Only fair—it can't withstand much force. 3 Pretty good—it takes a lot of force to break it. 4 Super strong! We can't break it.) They should find that the materials that are strongest in tension:  are the string, yarn, pipe cleaner, popsicle stick, ceramic tile, cardboard, drinking straw, cloth, rubber band (strong but very flexible), rubber eraser, paper-towel tubes and the pencil. The materials that are strongest in compression are the popsicle stick, clay (limited), ceramic tile, rubber eraser, paper-towel tubes (limited) and the pencil. The materials that are strongest in torsion are the ceramic tile, rubber eraser (limited), paper-towel tubes and the pencil.

Discussion

Which materials were strongest in resisting each type of force? Did any of these results surprise you? Why or why not? 

Which materials were strongest across all three tests? How would you describe those materials?

Discuss how some materials are flexible under a type of stress–they change shape as opposed to breaking outright. When might flexibility be desirable? When is stiffness required? (Parts of structures such as the cables of suspension bridges that are built to withstand shaking caused by wind gusts often have some "give." Other parts of structures, such as floor beams that support great weights, need to be rigid.)

How to Host an Paint Night Art Party (Paint and Sip or Coffee and Canvases)

It seems that Painting Parties, both Sip and Paint and Coffee and Canvases types, are all the rage right now. Did you know, however, that you can host an entire party for several friends for the price of about one admission to a standard paint and sip night?

This is not the painting we used for our party, but is another of the paintings you can do from The Art Sherpa's tutorials. This was done entirely by my autistic son, Alex.

How To Begin

Your first task if you want to host a party is finding a painting that you want to paint. This decision will be influenced by how artistic the host is, how experienced your guests are and their ages or if it is a mixed-age group. If you are artistic enough yourself, you could come up with your own design, perhaps with just a quick browse for what types of paintings are usually done in a party setting. Remember, you want your guests to be able to paint the entire painting in length of time of your party, typically a few hours.

Katie's painting of Happy Chickadee and Apple Branch

I used one of the over 700 acrylic painting tutorials offered for free by The Art Sherpa. She ranks the difficulty of her paints into three categories, between 1, for the easiest, to 3 for the most difficult. I chose Happy Chickadee and Apple Branch because it was a level 1 painting as some of my guests had never painted before. The nice thing about the tutorials is that even the easiest projects are not boring the the more advanced painter.

My painting of Happy Chickadee and Apple Branch. Note the slight variations between Katie's and my paintings. Be prepared for this. Even though we each watched the same tutorial, each person's painting turned out a little different...all good, but each a bit unique.

You, as host, should paint the projects yourself before the party. This gives you an example for your guests to look at in case they have a troubling point and keeps the steps in your mind so you can help if they need it. It also gives you a chance to troubleshoot any possible difficulties in advance.

Notice that I have the painting I did in advance set up on an easel for guests to refer to.
I also have set the paints all at one end of the table. They will be passed around as needed, so you don't have to buy a separate set of paints for each guest.

Buy The Supplies

I usually buy my supplies at Michael's simply because it is a one-stop shop for me (I live in the Boonies, so it is an hour long trip, minimum to any store) and they often have sales for the items needed (not everything all at once, though, so if you live near a store, you might want to go multiple weeks to see if they have more of the items you need on sale each week). If you have another craft/art supplies store near you, you might want to check on their prices. You can find the items you will need at Walmart or Amazon as well.

What will you need? Well, if you are choosing to use an Art Sherpa tutorial, she has a concise list at the bottom of her tutorial. Just click on the title and look at the description below. 

Acrylic Paint and Canvasses

You will need several colors of paint. For our Happy Chickadee painting, we needed seven colors (Burnt Sienna, Cadmium Red, medium shade, Cadmium Yellow, medium shade, Mars Black, Titanium White, Ultramarine Blue and Yellow Ocher), which is a typical amount of colors. If you go to a store like Michael's, you will find that there will be at least three grades of paint, ranging from the beginner's Artist Loft, which is less expensive (around $4 a tube) to the Golden's professional paint, which is the most expensive (around $9 a tube). If this is a one time event, you might not want to spend a whole lot on the paints. However, I did want to tell you that if you buy the least expensive paint, you might have more trouble with coverage as the companies of lesser quality paint save money by putting less pigment in their paints. They are certainly fine for a party, but just be aware that you might have to paint the canvas twice, especially at the places you use lighter color paints, such as white and yellows.

You will need one canvas per guest. I usually buy 16 x 20 inch canvasses. They often come in five-packs. They also come in grades. The lowest grades may also have paint coverage problems with the gesso on the canvas. Not a big deal, but just be aware that if the paint does not go on your canvas smoothly, it is probably not your fault, but the canvas'. You can solve this problem by just drying the paint and applying another coat of paint.

Brushes

source: Art is Fun!

You will need a variety of sizes and styles of brushes. I have found for the beginning painting lessons that it doesn't matter a whole lot if you have the exact brushes called for in the tutorial, but it is important to have a variety so that if one type of brush is not getting the results you want, you can try another one. Of course you will need enough for everyone at your party to have a variety to choose from. If you want to know more about brushes and how the different shapes affect painting, Art is Fun! has a great post on this subject. Brushes, like paint and canvasses, have levels of quality, which will affect how easy the painting is to accomplish. If you are not sure how much you will be painting, I would start with the least expensive ones and add to the collection if you get hooked on painting as I have. Professional brushes can get very expensive.

Other Supplies

You will also need either cloths or paper towels to wipe your brushes out and clean up any spills or messes. I love kitchen flour sack cloths, but paper towels work just fine and are inexpensive.

You will need a cup of water and something to use as a pallet for each painter. I used regular plastic cups and paper plates for this.

Your guests may want to use a piece of regular kid's chalk to sketch in their painting. You may also want to provide a table easel for each guest. We had a few around the house (I have a college student daughter who is majoring in art) but they are not necessary and many of our guests just painted with the canvas flat on the table. 

Unless you want to just watch the tutorial and then teach how to do the painting yourself, you will need to have a way to display the tutorial from YouTube. I set up a television so that all the guests could see it and my husband worked the technical side by stopping the video periodically while guests painted and caught up to the tutorial.

You will also need to cover your table (and maybe even the floor and chairs) with a dropcloth. I used a thin plastic tablecloth that I picked up for a dollar.

You may want to buy refreshments, whether they be wine or coffee any other beverages of your choice. You might also want snacks or even a dinner. Since we needed to have the background of the painting to be dry before painting in the rest of the painting, I set up our party so that we painted in the background of the painting and then set it aside. While this dried, we ate dinner and then after dinner was over, we went back to painting. This required two places, one for painting and one for eating, however. You could, instead, just have finger foods and have everyone eat standing up or sitting in the living room while the paint dries. We served wine coolers while we painted the second part of the tutorial. An alternative to allowing the paint to dry, is to use a hair dryer to dry the paint.

The Day of the Party

On the day of the party, set up any decorations you might want to use and set up your drop cloths. Set up individual painting stations with all the supplies your painters will need. I just set the paint tubes at one end of the table and we just squeezed out a bit of paint as we needed it and then passed the tube around the table.

Prepare any refreshments you are serving. If the tutorial has a traceable, you will want to print that out for any guest that wants to use it. I find that rarely do you need one for the level one tutorials, however, as she explains how to paint everything very clearly. If you want to use a traceable, you will want to watch this tutorial on how to transfer an image to canvas.

The Party

Unless you have invited all experienced painters, expect your guests to be nervous about their ability to paint. Prepare them to expect the paintings look like children's art until the final highlights and lowlights are added to the painting. Reassure your guests and be prepared to give them step by step help. You may choose to paint with them, or just be available to give them the help they might need. It's a good idea to take a break at some point, even if you are not serving refreshments.

I hope this post reassures you that a painting party is not too difficult to host. However you choose to do your party, an art party is an inexpensive way to have fun with friends in a way that is tailored to your and your guests.