2. WHAT ARE THINGS MADE UP OF?
We see innumerable things around us.
They look different and have properties
different from each other. Wood, steel, clay,
graphite, etc are examples of materials.
Materials are used to make different kinds
of objects.
There are different types of objects that are
made from same material.
4. ExPLANATION
:Appearance- Materials usually look different from each other. Wood looks very different
from iron. Materials such as metals have lustre whereas materials like wood doesn't have
shine. Some metals often loose their shine and becomes dull due to the action of air and
moisture on them. We therefore, notice the lustre only on their freshly cut surface.
Hardness-a)Materials that can be easily compressed or scratched are called soft materials.
Eg: Sponge, cotton.
b)Materials that cannot be easily compressed or scratched are called hard materials. Eg:
Iron, steel.
Soluble/Insoluble-Soluble materials- Substance that completely disappear in water are
called soluble substances. Eg: Salt, sugar.
Insoluble materials- Substances that don’t disappear in water are called insoluble materials.
Eg: Sand, soil
5. FLOATING AND SINKING
The mass per unit volume of a substance is known as density. A substance(iron,
aluminium) which is denser than water will sink in water. A substance (wood, cotton)
which is less dense than water will float on water.
TRANSPARENCY
You can see through a glass but not through a wood or metal plate. The objects through
which you can see clearly are called transparent materials. The objects through which
you can see but not clearly are called translucent materials.
The objects through which you cannot see at all are called opaque materials.
CLASSIFICATION
Classification means to sort materials into groups according to their similarities
and dissimilarities.
6. TRANSPARENT TRANSLUCENT AND OPAQUE
OBJECTS
TRANPARENT: The materials which pass all the light through them are called transparent
objects. example: clear glass
9. SUMMARY
• Objects around us are made up of a large variety of materials.
• A given material could be used to make a large number of objects. It is also
possible that an object could be made of a single material or of many different
types of materials.
• Different types of materials have different properties.
• Some materials are shiny in appearance while others are not. Some are rough,
some smooth. Similarly, some materials are hard, whereas some others are soft.
• Some materials are soluble in water whereas some others are insoluble.
• Some materials such as glass, are transparent and some others such as wood and
metals are opaque. Some materials are translucent.
• Materials are grouped together on the basis of similarities and differences in their
properties.
• Things are grouped together for convenience and to study their properties.