Unit D Section 3 Introduction Materials and Joints
Completion requirements
Section 3: The function of a structure depends on its joints and the material of which it is made.
Unit D: Section 3 – Introduction
Figure D.S.3.1 – These homes in Africa are made from dried mud.
Figure D.S.3.2 – These tent homes are made from animal skins.
Many possible materials can be used to build structures such as houses. Often, people choose building materials based on natural materials easily available. Sometimes people choose building materials for safety reasons or for aesthetic reasons.
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Likely, you have heard "The Three Little Pigs" tale. Watch this video to see a funny retelling of "The Three Little Pigs" story! What lesson can be learned from this tale about building with various materials?
Straw, Sticks, and Bricks
In real life, people build houses from various materials, including straw, wood, and bricks.
People in various cultures have built straw houses for thousands of years. Straw is the dry stems of grain plants -- the leftovers of a wheat or barley harvest, for example. Thus, it is very accessible. Straw is a good insulator, which means it keeps heat inside houses during winter, but also it keeps houses cool during summer.
In real life, people build houses from various materials, including straw, wood, and bricks.
People in various cultures have built straw houses for thousands of years. Straw is the dry stems of grain plants -- the leftovers of a wheat or barley harvest, for example. Thus, it is very accessible. Straw is a good insulator, which means it keeps heat inside houses during winter, but also it keeps houses cool during summer.
Figure D.S.3.3 – This straw house is located in northern Japan.
Figure D.S.3.4 – Straw bales fit tightly in the walls of this house.
Some modern houses use straw bales as insulation material, as you can see in Figure D.S.3.4.
Straw is also waterproof, so it is used as a roofing material. Houses with straw roofs, as in Figure D.S.3.5, are called thatched houses.
Straw is also waterproof, so it is used as a roofing material. Houses with straw roofs, as in Figure D.S.3.5, are called thatched houses.
Figure D.S.3.5 – Many houses in medieval times had thatched roofs.
Figure D.S.3.6 – The frame of a wood house.
Wood houses are very popular all over the world. Wood houses are quite inexpensive to build because wood is a readily available resource in most countries. In addition, wood is strong and flexible in high winds and earthquakes.
Bricks – Strong, But Not Very Flexible
Bricks are made of packed clay. Bricks are a strong building material that last a long time. They are more fireproof than straw and wood are.
Bricks are stiff and rigid, which means they topple easily in earthquakes. In earthquake-prone zones of the world, bricks are not the best choice of building materials.
Bricks are made of packed clay. Bricks are a strong building material that last a long time. They are more fireproof than straw and wood are.
Bricks are stiff and rigid, which means they topple easily in earthquakes. In earthquake-prone zones of the world, bricks are not the best choice of building materials.
Figure D.S.3.7 – A brick house.
Figure D.S.3.8 – Often, brick structures fall down during earthquakes.
Steel Houses?
Many people in large cities live in apartment buildings rather than in individual houses. Although small apartment buildings can be made of wood, the main materials in large apartment buildings are steel and concrete.
Many people in large cities live in apartment buildings rather than in individual houses. Although small apartment buildings can be made of wood, the main materials in large apartment buildings are steel and concrete.
Figure D.S.3.9 – A steel and concrete apartment building under construction.
Figure D.S.3.10 – Shipping containers can be stacked to make apartment buildings.
Some people live in apartments that are completely made of steel. The homes in Figure D.S.3.10 are made from recycled shipping containers!
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Steel Shipping Houses
Watch this video for a tour of a recycled shipping container steel home.
Watch this video for a tour of a recycled shipping container steel home.
In this section, you will learn more about how the materials and joints in a structure affect the function of a structure.
Words to Think About:
Words to Think About:
Check the word cloud below. It pictures important words used in this section. As you read, watch for these words and combinations of them. You can click them to learn more about their meaning.
Check the word cloud below. It pictures important words used in this section. As you read, watch for these words and combinations of them. You can click them to learn more about their meaning.
Lessons in This Section
Lesson D11: Material Properties
Key Question – How do we choose the best materials for a structure?
Lesson D12: Joints and Friction
Key Question – How are the parts of structures joined?
Lesson D13: Animal Joints
Key Question – How do joints in animals help them move?
Lesson D14: Protective Structures
Key Question – How are structures designed to provide protection?
Reading and Materials for This Section
Science in Action 7
Reading: Pages 308–323
Materials Lists for Unit:
Try It!
A Strong Straw House?
The big bad wolf blew down the little pigs straw house, but do you think you could design and build a straw house that could not be blown down?
Try this simple experiment at home. Everything you have learned about strong structures so far in this unit will help you!
Materials:
The big bad wolf blew down the little pigs straw house, but do you think you could design and build a straw house that could not be blown down?
Try this simple experiment at home. Everything you have learned about strong structures so far in this unit will help you!
Materials:
- drinking straws
- modelling clay
- masking tape
- hairdryer
Instructions:
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Design and build a house of straws that you think will not blow down. You can use as many straws as you like. Use modelling
clay and masking tape to help connect the straws.
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If you can, put the hairdryer on a cold air setting. Turn on the hairdryer at full power; aim the blowing air at your straw house. If you must use hot air, be careful to keep the hot hairdryer a safe distance from the plastic straws.
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Did your straw house stand up to the wind? If not, try making some changes to your house design; then, test its strength with the hairdryer again.
Questions:
Think about the following questions very carefully. Then, type or write your answers. When you have your answers, click the questions for feedback.
Think about the following questions very carefully. Then, type or write your answers. When you have your answers, click the questions for feedback.
A good foundation under a house helps it to stay in place. If you taped or weighted your house to a table, it probably did not blow away.
Strong shapes such as arches and triangles in a house design help resist shear force from wind pushing against the house.
Sturdy connections, or joints, between the straws help the structure not to blow apart easily.
Strong shapes such as arches and triangles in a house design help resist shear force from wind pushing against the house.
Sturdy connections, or joints, between the straws help the structure not to blow apart easily.