Topics
Natural Resources – Air, Water and Land
- Natural Resources
- Atmosphere and Its Layers
- Air Around Us
- Composition and Components of Air
- Importance of Air
- Air Pollution and Its Causes
- Water: Our Lifeline
- Availability of Water
- Composition of Water
- Importance of Water
- Scarcity of Water
- Land
- Soil Formation
- The Importance of Conserving Earth’s Natural Resources
The Living World
Diversity in Living Things and Their Classification
Disaster Management
Substances in the Surroundings –Their States and Properties
Substances in Daily Use
Nutrition and Diet
- Nutrients and Nutrition
- Component of Food
- Carbohydrates
- Diseases Due to Deficiency of Carbohydrates
- Fats (Lipids)
- Diseases Due to Deficiency of Fats
- Proteins
- Diseases Due to Deficiency of Proteins
- Vitamin and Minerals
- Diseases Due to Deficiency of Vitamin
- Diseases Due to Deficiency of Minerals
- Fibre
- Diseases Due to Deficiency of Fibre
- Water
- Diseases Due to Deficiency of Water
- A Balanced Diet
- Nourishment and Malnutrition
- Food Adulteration
Our Skeletal System and the Skin
Motion and Types of Motion
Force and Types of Force
Work and Energy
- Force, displacement and work
- Energy
- The relationship between work and energy
- Forms of Energy
- Mechanical Energy
- Heat Energy (Thermal Energy)
- Light Energy
- Sound energy
- Chemical Energy
- Transformation of Energy
- Energy Resources
- Conventional energy resources or non-renewable energy resources
- Non-conventional energy resources or renewable energy resources
- Energy saving and green energy
Simple Machines
Sound
Light and the Formation of Shadows
Fun with Magnets
The Universe
Man-made substances:
Man-made substances are materials that people create by changing natural substances into new forms. Humans do this because they always want to improve their lives and make things easier and more comfortable.
Humans process natural materials to create man-made substances for several reasons:
- Availability: These new substances can be made easily and in large amounts.
- Cost-effective: They are cheaper to produce.
- Usefulness: They are often easier to use in everyday life.
Earlier, irlis or capes made of grass or sackcloth were used to protect from rain. Then cloth umbrellas came into use. Nowadays, the raincoat, school bags, and book covers you use can all be made from plastic.
Delicate articles, perishable fruits, etc., require packing. To pack TV sets, refrigerators, etc., big cartons and thermocol are used. All these are man-made substances. They are waterproof or water-resistant, lightweight, and easy to transport, which is why they are being used increasingly.
- While making man-made substances, the properties of the constituents undergo a change due to certain chemical reactions.
- These changes in the properties are permanent; that is, the original constituent substances cannot be obtained again from the new substances. Such changes are called irreversible changes.
| Area of Use | Natural Substances | Man-made Substances |
|---|---|---|
| Construction | Bamboo, stone, soil, wood, coconut fronds, lime | Brick, cement concrete, galvanized sheets, clay tiles, plastic/asbestos sheets |
| Writing Material | Tree bark, leaves, bhurjapatre, pens made from reeds, dhulpatya, stone slates, stone walls in caves, soil and colours made from plants | Pens, pencils made from plastic and metal, paper, notebooks, etc. |
| Threads/Fibre/Yarn | Cotton, silk, wool | Nylon, rayon |
