Primary 4 Classes


Big Ideas

MatterSolid, Liquid, Gas

– Matter is anything that

a) has mass; and

b) occupies space (volume)

– Properties of Solid, Liquid and Gas

a) Definite/No definite shape

b) Definite/No definite volume

c) Can/Cannot be compressed

Light Energy – Properties of light
– Light and materials
– Shadows
Heat Energy– Sources of heat-
– Conductors and Insulators
– Movement of heat

Question 1:  Which pot, A or B, needs a longer time to boil the soup to 120oC? Explain.

Although the temperature of both pots is the same, pot B needs more heat to bring the pot of soup to the same temperature as that of pot A. Hence, pot B needs a longer time to boil to 120oC.

Primary 4 - Topic :Matter

What is Matter?

  • Matter is anything that has mass and occupy space.
  • Things that do not have mass or occupy space are not matter.

Examples of non-matter are shadow, heat, light, lightning, thunder, music, electricity, rainbow.

1. Matter has mass

  • Matter has mass. Mass is the amount of matter or amount of substance in a body or object.
  • Mass is measured in grams (g) or kilograms (kg).
  • Mass is not the same as weight.

2. Matter occupies space

  • The amount of space that an object occupies is called its volume.
  • In the diagram below, air occupies space in the conical flask, preventing the water from flowing into it.

Three States Of Matter

  • The atoms in a solid are packed closely together in a regular pattern. Thus, a solid has a fixed or definite shape.
  • The shape of a solid can be changed only if a force is applied to it.
  • It only changes its shape if we bend, dent, break or stretch it.
  • When we said the solid cannot be compressed, it means that the volume of the solid cannot be changed or compressed to occupy a smaller space

  • The atoms in a liquid are not held in a regular pattern and are not packed as closely as those in solid. Thus, a liquid has no definite shape. It takes the shape of the container. The volume of a liquid remains the same when it is poured from one container to another.
  • There is still very little space between atoms, therefore, they can not be pushed together to occupy a smaller space. Thus, a liquid cannot be compressed and has a definite volume.
  • A syringe contains water. The plunger cannot be pushed in any further because water cannot be compressed.
  • The atoms are widely spaced in an irregular manner. As a result, they have indefinite shape and indefinite volume. Hence, a gas takes the shape of its container.
  • The large spaces between the atoms enable the particles to be forced together to occupy a smaller space.This means that gas can be compressed.
  • The volume of a gas can be changed– it can be either compressed to occupy a smaller space or expanded to occupy a bigger space.
  • The table tennis ball became smaller and took up less space when it was squeezed. The air inside was compressed.

A summary table:




Solid (cm3)Definite shapeDefinite volumeCannot be compressed
Liquid (ml)No definite shapeDefinite volumeCannot be compressed
Gas (cm3)No definite shapeNo definite volumeCan be compressed


1)Wrong concept: Plasticine is not a solid as it has no definite shape.

Right concept: A solid can only change its shape if a force acts on it.

Plasticine does not change its shape when it is not moulded.

2)Wrong concept: Substances like salt and sugar are not solid because they take the shape of the container.

Right concept: Each grain of sand or sugar is a solid. It is small so many that it can fit into a container.


3)Wrong concept: Weight is the same as mass.

Right concept: Mass is the amount of matter in a body. It does not change.

Weight is due to the gravitational force applied on an object and can change.


4)Wrong concept: Gases do not have mass or weight.

Right concept: Gases are matter and thus have mass and weight.