DON'T STRESS OUT!

DON'T STRESS OUT!

MASTER TEACHER Lori Morrison

GRADES 3-5

OVERVIEW
This lesson provides students with a basic understanding of various types of structures. Video segments have been selected to introduce students to significant factors that identify forces that structures must withstand. Video, hands-on investigative and interactive activities were chosen to portray construction techniques that result in sturdy buildings. Students investigate tensile stress and compression stress. Students discover that "form follows function" in natural and man-made structures.

ETV SERIES
Bill Nye: #106 Structures

LEARNING OBJECTIVES
Students will be able to:
*identify the forces that structures/buildings must withstand
*describe construction techniques that result in sturdy buildings
*apply knowledge of mathematical shapes to actual structures/buildings
*identify properties of building materials
*identify which properties of building materials are important to make a sturdy structure
*reinforce basic mathematics computational skills (addition and subtraction)
*construct a freestanding structure that has the capacity to hold a top weight

MATERIALS
per class:
set of wipe off markers
pictures of man-made structures
safety goggles (class set)
glass bowl
100ml flour
100ml salt
100ml water
1 tsp cooking oil
1 tsp cream of tartar
microwave oven
vinegar
tongs
candle
matches
thermal gloves
six plastic screw top bottle caps
three raw eggs
three patio bricks (flat) or flat hardback dictionaries

per group:
play money (Amount according to grade level ability 3 digits / 2 digits etc.)
various types of pasta
masking tape (1 roll)
six ping pong balls
six 1 x 1 foot cardboard pieces

per student:
one Bill Nye worksheet

VOCABULARY
arch - a curved part of a structure that hold up the weight of material over an open space.
compression - to press or squeeze closely together.
compression stress - results when two forces push toward one another through solid material, causing it to compress, or shorten.
dome - a round roof shaped more or less like half a globe.
flexibility - bends easily without breaking.
force - the power to cause, stop or change motion.
material - of or having to do with matter.
property - any of the special qualities by which a thing is known; characteristic.
rigid - not bending or moving; stiff and firm.
stability - the condition of being stable; steadiness; firmness.
structure - something built; a building, bridge, dam, etc.
tensile stress - opposite forces are applied equally.
tension - a stretching or being stretched, so as to put or be under strain.
shear stress - occurs when opposite and equal forces work to change the shape of an object because the lines of force are not directly across from each other.

PRE-VIEWING ACTIVITIES
Show students pictures of different man-made structures. Show students a plant. Tell students that there are many types of structures in our world. Tell students that we are going to investigate various structures. Tell students that all structures have to be built to be strong enough to resist the many different forces that act on them. Tell students that the strength of a building depends on materials that are used and the shape of the materials. Materials have properties that help keep a structure standing.

Experiment: Investigate Properties of Materials
Procedure
1.) In a microwave bowl, mix 100mL each of flour, salt, and water. Add one teaspoonful each of cream of tartar and light cooking oil.
2.) Heat the material in a microwave for 1 minute. Allow to cool.
3.) Break off small samples for testing. Test one sample to see how it reacts to water. Test one with vinegar and one with a lit candle. (immerse in liquids) Students observe and record any changes.
4.) Shape some of the material into a small column. Observe/record the columns ability to support various classroom objects.
Student observations:
Students will observe that the material made changes in consistency after heating. When placed in vinegar it decomposes. When placed in water the material softens. The material does not burn, but does char. After shaping the material into a column, students will realize that shorter, thicker columns support the most mass.
Tell students that it is important to use our knowledge of the properties of materials when looking at and building structures. Ask students if they remember a story about a wolf that blew down some houses. Buildings/structures must be able to withstand certain forces so they may stay standing. The strength of a structure is determined by what it is made of and how the material is put together.

FOCUS FOR VIEWING
To give students a specific responsibility for viewing say, "You are going to see a video with Bill Nye talking about structures. I want you to listen and list, on the ëStructures' worksheet, list the structures Bill mentions."

VIEWING ACTIVITIES
Begin tape Bill Nye #106 Structures as Bill Nye is swinging on a rope in his laboratory. Audio is Bill saying, "I'll bet you are standing or sitting on a structure." Pause video with visual of Bill walking to a model suspension bridge. Audio is Bill saying, "Let's face it, structures are cool." Review worksheet answers to the question of what structure does Bill mention. (Structures mentioned are; chair, floors, ropes, sliding doors, and cat whiskers.) Ask students to look at the model suspension bridge on the television screen. Show students by using a wipe off marker how the model bridge is displaying two forms of stress. Tell students that in order to prevent buildings from collapsing, every force must have a counter force pushing or pulling in opposite directions (similar to a game of tug of war). Have students fill out the definition of tensile stress and compression stress on their worksheet. (tensile stress - results when opposite but equal forces are applied, causing a solid to lengthen. / compression stress - results when two forces push toward one another through a solid material, causing it to compress, or shorten.) Tell students to listen to Bill as he talks about the bridge structure. Ask students to listen so they may explain the phrase "form follows function", and the roles of tension and compression. Resume tape. Pause tape with Bill running off the bridge. Audio is Bill saying, "Structures are a tension and compression party." Review worksheet answers. (Form follows function refers to the shape of a structure supporting the purpose of the structure. Wires - are thin and in tension. Posts are thick and in compression.) Tell students that Bill is going to visit another structure, Hoover Dam. Tell students to listen to Bill as he tells why Hoover Dam is curved. Fast forward video to visual of Bill in a safari hat with Hoover Dam behind him. Audio is Bill saying, "This is Hoover Dam." Resume tape. Pause tape with visual of words "Did you know thatÖ" Audio is Bill yelling, "Did you know thatÖ" Ask students to describe the shape of Hoover Dam. (curved like an arch to hold water pressure) Discuss how water pressure is held back by the curved shape. Answer worksheet question; Hoover Dam is curved, it is in compression. Before resuming the tape, tell students that you want them to finish Bill Nye's next two statements. (Write answers on the worksheet) Resume tape. Pause tape with visual of words; Structures come in almost every shape. Audio is Bill stating the former. Discuss the two statements Bill made. (Structures are everywhere and can be almost anything, not just buildings and bridges. Structures come in almost every shape.) Ask students to look around the classroom and see if they can locate any structures. Tell students to list at least six structures seen in the classroom on their worksheet. After sharing answers, tell students that you want them to list all the structures they see in the next video segment on their worksheet. Resume tape. (Replay tape if needed.) Pause tape. Visual is printed words; Did you know that form follows function. Audio is Bill saying, "Now you know." Discuss structures shown. Tell students to watch the tape to see what a natural structure is, what type of stress tree trunks are in, and why they are thicker at the bottom. Resume. Pause tape with Bill saying, "Science and nature, nature and science." Video is Bill standing at the trunk of a tree. Go over worksheet answers. (Plants are natural structures. Ask students to name other natural structures that we have talked about today. Tree trunks are in compression. Tree trunks are thicker at the bottom to hold the weight of the smaller branches and leaves. Now, tell students you want them to listen carefully so they can determine what shape a structure should be. Resume. Stop tape with visual of Bill trying to open a white car. Audio is Bill saying, "So are you getting a handle on this structure thing?" Ask students to answer the worksheet question. (The shape of structures depends on what they do and what they are made of.) Ask students if they have a handle on this structure thing. The shape of a structure depends on what it does and sometimes it works with another structure. Tell students that we will experiment with some specific shapes. Dome shapes are strong and withstand forces. Tell students that using a triangular shape and a dome shape we are going to make an egg tower. Mention that eggs spread the force of weight evenly around the sides of the egg and the triangle shape is more resistant to change. The former is why many structures are triangular shaped.

Experiment:
Place three raw eggs in three plastic (3 liter) bottle caps in a triangle. Place three more bottle caps on top of the eggs. Carefully place a patio concrete block (or large hardback book) on the triangular egg pattern to prove that the dome/triangular structure is indeed strong (eggs won't break). Add two or three more blocks or books to the structure to show students the large amount of weight the eggs can hold (compression stress). The eggs hold the weight due to their shape and the placement of the eggs in a triangular pattern. Tell students that they have learned how structures can support and work in various ways. Ask students if they are ready to build a structure that can show a tension and compression party?

POST-VIEWING ACTIVITIES
Review Structures worksheet going over terms and statements made during the video. Tell students that they now have the task of building a pasta tower. Their pasta tower will have to be built with pasta and tape. Students, in groups, who build the tallest pasta tower will win the contest. Students need to use their knowledge of tension and compression by attaching a ping pong ball to the top of their pasta structure. The tallest structure with a ping pong ball attached to it that is still standing when the timer goes off is the winner of the Pasta Tower Challenge Contest. *There is also a second competition. At the beginning of the contest each group gets the same amount of play money. Students use the money to buy pieces of pasta and masking tape. Once the students run out of money, they cannot buy more materials to build their structures.

ACTION PLAN
Visit the city or county courthouse and talk to a civil engineer or a city building code inspector. Have the engineer show what criteria must be met for building a structure in the community. Have students prepared to ask area specific questions (i.e. Corpus Christi building codes for Padre Island). Discuss the shape of structures and the best materials for those structures.

EXTENSIONS
Language Arts
Make some shape poems. Students write poems about a structure. The poem is actually the outline of the structure, Fence Post.STANDS
TALL
IN THE
GROUND
HOLDS
MANY
BARBED
WIRES

Mathematics
Visit
forum/swarthmore.edu/~isaac/mathhist.html Within this web site, students can investigate problems that have inspired mathematicians throughout history. Also, the site includes links to solutions, biographies, and other mathematical history sites. Have the student's research Fibonacci. Have the students find the Fibonacci sequence. Present the students the following problem: you have to build a structure using the Fibonacci sequence and cans. Should you start from the bottom up or the top down and why? Build the structure and then recycle the cans! This works best when you give students different amounts of cans to work with.

Architecture/ Structural Engineering
Language/Composition
Invite a structural engineer and an architect to talk about structures. Ask them to compare and contrast their jobs. View the Eddie Files #3 Invasion of the Polygons. Have students write a comparison/contrast composition about the two different occupations.

Physical Education
Have cheerleaders (or a tape of cheerleaders) show your students the various human pyramids that they make. Discuss the triangular design of the larger pyramids. With spotters, have the students create smaller human structures. Have the students make up school cheers using their human structures.

HANDOUT

Name_____________Date_______Class______ STRUCTURES 1.) Structures
       a._____________
       b._____________
       c._____________
2.) tensile stress- _________________________
3.) compression stress-_____________________
4.) "form follows function" means
      wires are ________and are showing_______
      posts are ________and are showing_______
5.) Hoover Dam is________, it is in__________.
6.) Structures are_________and can be almost
      __________. Not just buildings and bridges.
     Structures come in almost every__________.
7.) Classroom structures list:

8.) Structures
     ______________   ______________
     ______________   ______________
     ______________   ______________
9.) ___________ are natural structures.
10.) Tree trunks are in_____________, because
       ___________________________________
11.) The shape of structures depends on what they ________, and what they're____________.

Updated: April 01, 2008