Solids and Their Properties

• Define a solid and list its main properties.
• Identify common solid materials at home and school.
• Explain why solids keep a fixed shape and volume.
• Connect the idea of solids to everyday Indian examples.

Level 1 - Meaning of a solid

A solid is a material that has a fixed shape and a fixed volume. Whether kept in a box, a bag, or on a table, a solid such as a stone, a book, or a pencil does not change its shape on its own.

Level 2 - Why solids keep their shape

Inside a solid, the tiny particles are packed very close together and only vibrate in place. Because they cannot move past each other, the solid cannot flow and keeps the same shape and size.

Level 3 - Hard and soft solids

Solids can still be hard, like iron and stone, or soft, like cotton and sponge. Even a soft solid keeps its own shape when placed down, unlike a liquid which spreads out.

Level 4 - Indian context

Chalk, slates, and wooden desks used in Indian classrooms are all solids. Clay used by potters in towns like Khurja can be moulded by hand into new shapes, but the clay stays a solid throughout the moulding.

NCERT anchor: Looking Around 4, Ch 1 — Moving Around / general observation of materials (solid objects around us)

Checking if sand is a solid

Step 1 - Take a spoon of dry sand in your hand.
Step 2 - Try to pour it slowly like water.
Step 3 - Notice it forms a small heap instead of spreading flat like a liquid.
Step 4 - Each grain of sand keeps its own tiny fixed shape.
Answer: Sand is made of many small solid grains, each with a fixed shape.

Comparing a stone and water

Step 1 - Put a stone in a round bowl.
Step 2 - Observe that the stone keeps its own shape, not the bowl's shape.
Step 3 - Now pour water into the same bowl.
Step 4 - The water spreads out and takes the shape of the bowl.
Answer: The stone is a solid because it keeps its own shape; water is not.

• What are the two main properties of a solid?
• Name three solid objects you can see in your classroom.
• Why can a solid not be poured like a liquid?
• Is a soft material like cotton still a solid? Explain.
• Stretch: Explain why breaking a stick into two pieces still leaves you with two solids.

Revision tip: A solid keeps a fixed shape and a fixed volume, wherever it is kept.

Open the Practice tab for graded questions on Solids.