Observing Objects Around Us

Have you ever wondered what materials are used to make the objects around you?

Let’s explore some common materials and see where we find them!
1. Paper: Used in books, newspapers, and packaging materials.
2. Wood: Used in furniture, construction, tools, and decorative items.
3. Cloth: Used in clothing, curtains, and upholstery.

Objects around us are made from different materials. A material is a substance used to make an object. For example, a wooden table is made from the material wood.

Some of Common Materials

• Paper: Used in books, newspapers, and packaging materials.
• Wood: Used in furniture, construction, tools, and decorative items.
• Cloth: Used in clothing, curtains, and upholstery.
• Glass: Used in windows, bottles, eyeglasses, and decorative items.
• Metal: Used in construction, machinery, utensils, and tools.
• Plastic: Used in containers, toys, electronics, and everyday items.
• Clay: Used in pottery, bricks, sculptures, and decorative items.

The Early Pottery in India 

• The oldest pottery found in the Indian subcontinent is believed to be around 7,000 to 8,000 years old, discovered in places like the Ganga plains (specifically Lahuradewa) and Baluchistan (particularly Mehrgarh). 
• Around 4000 BCE, the Sindhu-Sarasvati region saw advancements in pottery techniques, including wheel-turned pottery, the use of pigments, and the application of protective or decorative coats known as 'slips.' These slips came in multiple colors and often featured decorative paintings. 
• During the Sindhu-Sarasvati (or 'Harappan') Civilization, which lasted from 2600 to 1900 BCE, pottery techniques became even more sophisticated. Potters created bright red pottery with black designs that displayed geometric patterns and images of animals, both aquatic and terrestrial. 
• The clay used for making various pottery items, such as pots, dishes, and bowls, was carefully selected, cleaned, sieved, kneaded, and shaped on a potter's wheel before being baked in kilns. This process resulted in what is known as 'terracotta.' 
• Pots served a variety of purposes, including cooking and storing food items like grains, oil, and ghee. Some large storage jars and other pottery pieces can be seen at the National Museum in New Delhi.

How to Group Materials?

Can you explain why we group objects and how it helps us?

We group objects to understand them better. Grouping helps us find things more easily and see how they are similar or different. For example, when you group your toys by type or color, it keeps your room tidy and makes it easier to find the toy you want!

Let’s Discuss Classification of Materials:

• Objects can be made from different materials, and some materials can be used to create more than one object.
• The process of arranging objects into groups based on common properties is called  classification. Similarly, materials can also be classified based on certain properties.
• The choice of materials for making an object depends on the properties of the materials and the purpose for which the object is intended. For example, different parts of a pen may be made from different materials like  plastic, metal, and ink.

Examples of Grouping

• Shape: Round (ball), square (box), cylindrical (tube).
• Color: Red (apple), blue (sky), green (leaf).
• Hardness: Hard (stone), soft (cotton).
• Softness: Soft (rubber), hard (metal).
• Shine: Shiny (metal), dull (wood).

What are the Different Properties of Materials?

1. Observe and identify appearance of materials

Materials have different appearances. For example, freshly cut, unpolished wood looks very different from iron. Iron, copper, and aluminum also look different from each other, but they share some similarities that set them apart from wood.
Let's take on a sorting challenge:

Sorting Challenge 

• Gather small pieces of  paper, cardboard, woo, chalk, copper wire, aluminum foil, and any item made of  brass, bronze, steel, etc.
• Examine the collected pieces. Do any of them shine when light hits them?
• Observe their  texture  (rough or smooth), color, and other noticeable features. Record your observations in a notebook.
• Group the pieces based on their appearance.

 Lustrous vs. Non-Lustrous Materials 

• Lustrous materials  have shiny surfaces and are typically metals, such as iron, copper, zinc, aluminum, and gold. However, some metals can lose their shine and appear dull due to exposure to air and moisture. This is why we often see their shine only on freshly cut surfaces.
• Non-lustrous materials  do not have shiny surfaces. Examples include paper, wood, rubber, and jute.

Are all lustrous materials metals? 

• Not all shiny materials are metals. The saying  "All that glitters is not gold"  reminds us of this. 
• Some materials are made shiny by polishing or by coating them with thin layers of plastic, wax, or other substances. These materials may not be metals.

2. Which materials are hard?

• Materials that are easy to compress or scratch are considered soft, while those that are hard to compress or scratch are considered hard. However, these properties are relative. 
• For example, rubber is harder than sponge but softer than iron. This means that hardness and softness can change depending on what you are comparing.

3. Explore materials through which one can see or cannot see

Can you tell if water is transparent?

Yes, water is considered transparent because you can see through it clearly. However, if water is made opaque, for example, by adding something that prevents light from passing through, then it would no longer be transparent.

Let’s Discuss Types of Materials:

• Transparent Materials: Transparent materials are those through which we can see objects clearly without any distortion. Examples include glass, water, air, and cellophane paper.
• Opaque Materials: Opaque materials do not allow any light to pass through, which means we cannot see through them at all. Examples of opaque materials include wood, cardboard, and metals. 
• Translucent Materials: Translucent materials allow light to pass through, but they do not provide a clear view of the objects on the other side. Examples of translucent materials include butter paper and frosted glass.

4. What is soluble in water; what is not?

Can you explain what happens when we mix different materials in water?

When we mix materials in water, some, like sugar and salt, disappear completely because they dissolve in water. Other materials, like chalk powder, sand, and sawdust, don’t dissolve and stay mixed with the water for a while before settling down or floating. This shows that not all materials behave the same way in water!

Let’s Discuss Soluble and Insoluble Materials:

• Soluble Materials:  Some materials can dissolve in water. This means they mix well with water and disappear, like when you stir sugar into a cup of water.
• Insoluble Materials:  Other materials do not dissolve in water, no matter how much you stir. These materials remain separate and visible, like sand in a glass of water.
• Water is very important for our bodies because it can dissolve many different substances, helping our body function properly.

Mixing of Liquids and Solubility of Gases in Water 

• Some liquids mix well with water and become a part of it, like  sugar in water. 
• Other liquids do not mix with water and form a separate layer, like  oil . When left still, oil floats on top of water because it is less dense. 
• Just like liquids, some gases can dissolve in water while others cannot. 
• For example,  oxygen gas dissolves in water and is essential for the survival of  fish  and other aquatic animals. Plants in water also need dissolved oxygen  for respiration. 

Make Your Own Oral Rehydration Solution (ORS)

ORS, or Oral Rehydration Solution, is a simple and effective way to treat dehydration caused by diarrhea or other illnesses. While you can buy ready-made ORS packets at health centers or in stores, making it at home is easy and just as effective.

To prepare ORS at home, follow these steps:

1.  Take 1 liter of boiled and cooled water. 
2.  Add 6 teaspoons of sugar (which helps provide energy and restore lost fluids). 
3.  Add ½ teaspoon of common salt (which helps to balance the electrolytes). 
4.  Mix the solution well until the sugar and salt are completely dissolved. 

5. How heavy or light?

• Mass is a property we use to measure how heavy or light an object is. 
• When we say an object is heavier, it means it has more mass. Conversely, if an object is lighter, it has less mass.

Weight is often used interchangeably with mass in everyday language, but it specifically refers to how heavy something is when measured.

6. Space and Volume

• Volume refers to the amount of space an object occupies. 
• The volume of a liquid is usually measured in liters (L) or milliliters (mL).

What is Matter?

• Anything that takes up space and has weight is called matter.
• The amount of matter in an object is called its mass. We measure mass in grams (g) or kilograms (kg).
• The space taken up by matter is its volume. We measure volume in litres (L) or millilitres (mL).

Classifying Materials

• We can group materials based on their similarities or differences. For example, metals like iron, copper, and aluminum can be grouped together because they are all metals.
• Grouping materials helps us observe patterns in their properties. For example, metals are usually shiny, strong, and good conductors of heat and electricity.

 Unit of Mass: Kilogram (kg)

• The kilogram (kg) is the basic unit of mass in the International System of Units (SI). 
• When writing it, remember: no space between the "k" and "g," and no full stop after "kg," unless it's at the end of a sentence. 
• For example: 7 kg (not 7 kgs). 

Units of Volume: Litre, Millilitre, and Cubic Metre

•  The litre is written as a capital "L" (L), while the millilitre is written as "mL" with a lowercase "m" and an uppercase "L." 
•  For example: 500 mL (not 500 ml or 500 ml). 
•  The SI unit for volume is the cubic metre, abbreviated as m³. This is written with a superscript "3" to show that it is cubic. 
•  For example: 2 m³ (not 2 m³). 
•  When writing these units, always leave a space between the number and the unit. 
• Note: 1 m³ is equal to 1000 litres (L). 

Ayurveda and the 20 Properties 

In ancient India, there was a system similar to modern classifications, especially in Ayurveda, the Indian medical system. The  Ashtanga Hridaya,  an important Ayurvedic text, describes a method of grouping things by their properties. This grouping is based on the  20 properties,  which are ten pairs of opposite qualities used to describe all physical matter, living systems (like plants, animals, and humans), the environment, and even food.

Key Concepts

• Variety of Materials: Objects can be made from one or multiple materials.
• Classification Methods: Grouping based on properties such as appearance, hardness, transparency, and solubility.
• Properties of Materials: Determine their use and behavior.
• Concept of Matter: Defined by mass and volume.