Materials - Grade 7 Pre-Technical Studies Revision Notes

What you get:

• Materials
  • Definition of materials
  • Common materials
  • Identifying common materials in the locality
  • Categorising common materials in the locality as either metallic or non metallic
  • Distinguishing between metallic and non metallic materials
  • Physical properties of materials found in the locality
  • Careers related to materials in the locality
  • Importance of materials found in the locality
• Metals
  • Different types of metals in the locality
  • Identification of metals by surface appearance
  • Physical properties of metals
    • Ferrous and non ferrous
    • Magnetic and non magnetic
    • Conductors and non conductors of heat
    • Conductors and non conductors of electricity
  • Uses of metals in the locality
  • Careers related to uses of metals
  • Importance of metals
• Non-metallic materials
  • Distinguishing between synthetic and natural non metallic materials
  • Categorising non metallic materials in the locality as either natural or synthetic
  • Physical properties of non metallic materials
  • Uses of non metallic materials in the locality
  • Careers related to processing and use of non metallic materials
  • Effects of common Problems affecting the community
  • Skills need to solve problems in the community

MATERIALS

Any useful substance is called a material

COMMON MATERIALS

1. Timber
2. Sand
3. Stones  

Identifying common materials in the locality

Different localities have different common materials

Examples of common materials are

1. metals
2. Soil
3. Reeds
4. Sisal fibres
5. Hides and skins
6. Trees
7. Diatomite
8. Soapstone
9. Soda ash
10. Fluorspar

Categorising common materials in the locality as either metallic or non metallic
Pupil’s activity

Distinguishing between metallic and non metallic materials

Physical properties of materials found in the locality

Careers related to materials in the locality

1. carpentry
2. carving
3. masonry
4. welding  
5. pottery
6. weaving
7. blacksmith
8. farming
9. mining

Importance of materials found in the locality

1. create job/employment opportunities
2. improves the standard of people living in the locality   

METALS

Metals occur naturally within the earth’s surface

They are mined and converted into forms that are easy to use

Metals are used to make various items we use in our day to day life

Different types of metals in the locality

Some metals exist in pure form or as alloys

An alloy is a combination of a metal with another metal or metal with a non metal

Examples of pure metal

1. Aluminium
2. Iron
3. Zinc
4. Silver
5. Copper
6. Lead
7. Magnesium
8. Tin
9. Gold

Examples of alloys

1. Steel
2. Brass
3. Bronze

Metals can be identified easily by their surface appearance

Physical properties of metals

Identification of a metal by its physical appearance is not a sure way of knowing the exact type of metal

There are some other physical properties that we need to consider to correctly identify the metals

Metals can further be identified as

1. Ferrous and non ferrous
2. Magnetic and non magnetic
3. Conductors and non conductors of heat
4. Conductors and non conductors of electricity

Ferrous and non ferrous

Ferrous metals are metals that contain iron in its original form or alloys or iron

Non ferrous metal are metals that contain iron

Magnetic and non magnetic

Magnetic metals are metals that are attract by magnet if it is brought near.

Non magnetic metals are not attracted by a magnet

Conductors of heat in metals

1. Copper
2. Aluminium
3. Graphite
4. Silver
5. Gold
6. Steel spoon

Conduction of electricity

1. Zinc strip
2. Silver strip

NB

Metals are good conductors of heat and electricity although some metals may be better conductors than others.

Uses of metals in the locality

Careers related to uses of metals

Importance of metals

Metals are important in the locality in many ways

1. People purse careers related to metals, they earn a living
2. It helps people improve their living standards
3. Metals are important in making most items such as kitchen and farming tools which will be used to perform different tasks within the households.
4. Can earn the government foreign exchange if imported to other countries

Non metallic materials

Are any materials both synthetic and natural which do not contain metal

Distinguishing between synthetic and natural non metallic materials

Natural materials are those that exists on their own in or the earth without any actions of humankind.

They may be part of the earth material or from plants and animals.

Synthetic materials are those that are created by human beings through different process.

Natural non metallic materials include soil, timber, reeds, rubber, stones, hides and skins, plant fibres like banana fibres, sisal fibres, cotton and linen

Categorising non metallic materials in the locality as either natural or synthetic

Pupil’s activity

Physical properties of non metallic materials

Different types of non metallic materials have different properties

Uses of non metallic materials in the locality

1. Fibres like cotton and line are used to make cloths.
   Cloths re then made into different types of garments that we wear.
2. Rubber is used to make Items such as tyres, erasers and footwear
3. Timber or wood is used to make furniture, doors, floors, ceilings and walls of some houses. Wood is used as fuel in most homes.
4. Different types of soil have different uses
   Sand soil is mixed with ballast, cement and water to make concrete for constructon.
   Loam soil is used for farming
   Clay soil is used in pottery and brick making.
5. Grasses and reeds are used to make items like mats, baskets and brooms
   Grasses are also used as roofing materials
6. Hides and skins are used to make shoes, belts and bags
7. Glass is used to make window panes and household items like furniture and utensils.
   It is also used in making laboratory equipments such as test tubes.
8. Plastic is used to make items such as utensils, cutlery, footwear, buckets, basins
9. Minerals such as soda ash are used to manufacture soap, paper and glass.

Careers related to processing and use of non metallic materials

1. ROPE MAKING
   Rope makers harvest sisal fibres, dry and use them to make ropes
2. Building and constructions
   Builders use timber, grass, clay and other materials to construct houses.
3. Brick making
   Brick makers make bricks from clay soil.
4. Logging
   Loggers are authorised to cut trees selectively from a given area to get logs.
5. Saw milling.
   Saw millers cut the logs into timber or shapes them into boards.
6. Carpentry
   Carpenters use timber and boards to make furniture and other useful items.
7. Pottery
   Potters make pots and other earthen items.
   Some potters may also use of cement or concrete to make flower pots and flower vases
8. WEAVING
   Weavers make baskets, mats brooms, and other items from grasses and reeds
   Plastic straws can also be made in weaving
9. FARMING
   Crop farmers cultivate the soil using hand tools or farm machinery and plants crops into it
10. GLASS SMITHING
    This is a career where people are involved in making objects out of glass
11. SHOE MAKING
    Shoe makers make shoes from non metallic materials like leather, rubber and plastic

Identifying common problems in the community

Pupil’s activity

Effects of common Problems affecting the community

Pupil’s activity

Skills need to solve problems in the community

Some of the problems can be solved by learners, intervention of adults, experts or the government

When solving these problems, we apply some of the technical skills that we have  learnt.

We can also involve other members of the community who have the skills and experience

Example of technical skills  are

1. Masonry skills
   Are applied where structures such as houses, water pans and animal housing need to be constructed
2. Carpentry skills
   Are applied when joining pieces of wood to make desired items
3. Design and drawing skills
   Are applied where items or structures need to be sketched or drawn before they are made
4. Farming skills
   Are applied when carrying out activities such as digging, planting, weeding and when using farming tools and equipments
5. Sewing skills
   Are applied when joining and mending pieces of fabric to make desired items
6. Welding skills
   Are applied when joining materials to make desired items