P4 Science Topical Notes (Latest MOE PSLE Syllabus)
Updated: Mar 21
Primary 4 Science strengthens students' observation and explanation skills through three core themes: Systems, Cycles, and Energy. In Systems, they examine plant parts and functions, plus the human digestive system (mouth, stomach, intestines). In Cycles, students sequence life cycles of plants and animals, identifying main stages over time. In Energy, they explore forms and uses of light and heat, including everyday applications and basic effects. These topics build inquiry foundations for PSLE success.
Last updated 20 January 2026
Chapter 1: Plant System (Plant parts and functions) [Systems]
Parts of a plant & their respective functions
Roots
Anchoring the plant firmly to the soil
Absorbs water and mineral salts from the soil
Stem
Hold the plant upright and support the plant
Transport water, mineral salts and food
Leaf
Leaf stalk, leaf blade, veins
Allows gaseous exchange through the stomata
Contains chlorophyll to trap sunlight to carry out photosynthesis and make sugar
Flower (learn in P5)
Has male and female reproductive parts for reproduction of plants
Fruit (learn in P5)
contains seeds which can germinate into young plants
We will explore the transport system of a plant in P5.
Chapter 2: Human System (Digestive System) [Systems]
A system is made up of 2 or more parts working together.
All animals and plants have systems performing their functions. Plant has transport systems while human has various systems.
The systems work together in our body to ensure our body is performing properly.
Types of human systems in the body:
Digestive system
Respiratory system
Circulatory system
Skeletal system (detailed knowledge not tested)
Muscular system (detailed knowledge not tested)
Organ Systems (humans) | Organs | Functions |
Respiratory system |
|
|
Circulatory system |
|
|
Muscular system |
|
|
Skeletal system |
|
|
Human digestive system
Mouth (digestion starts)
Teeth: chew food into smaller pieces, increasing the surface area of food that is in contact with the digestive juices, hence digesting the food faster.
Saliva:
Mixed with food to soften the food so that it can be swallowed easily.
Contains digestive juices to break down some food into simpler substances.
Gullet (no digestion)
Helps to transport food from the mouth to the stomach.
Stomach (digestion)
Contains digestive juice to break down some food into simpler substances.
Small intestine (digestion occur & ends here)
Releases more digestive juices to break down some food into simpler substances and completes digestion
Blood vessels in the walls of small intestine helps to absorb digested food into the bloodstream
Large intestine (no digestion)
Absorb water from the undigested food into the bloodstream.
Parts containing digestive juices: Mouth, Stomach, Small intestine
Undigested food | Digested food | ||
Highest (entering/leaving) | Lowest (entering/leaving) | Highest (leaving) | Lowest (entering/leaving) |
Mouth | Large intestine | Small intestine | Mouth |
Chapter 3: Matter [Cycles]
Matter is anything that has mass and occupies space (has volume).
Mass is the amount of matter in an object.
measured using a beam balance or electronic balance
units are kilograms (kg) or grams (g)
Volume is the amount of space occupied by an object.
measured using measuring cylinder or syringe
units are cubic centimetres (cm³), cubic metres (m³), litres (l) and millilitres (ml)
Three States of Matter
Definite shape | Definite volume | |
Solid | Yes | Yes |
Liquid | No | Yes |
Gas | No | No |
A substance exist as solid/ liquid/ gas depends mainly on its temperature.
Liquids and Gas have no definite shape: take the shape of the container
Gases have no definite volume: allows them to be compressed/ occupy the remaining space in a container.
Displacement
Matter occupies the space previously occupied by another type of matter
Fully submerged a solid into a beaker of liquid that is filled to the brim
the amount of water flowing out (displaced) is the volume of the entire solid
Find volume of solids:
Fill measuring cylinder with water and measure the water
Lower the solid into the water, ensuring that the solid is fully submerged in water
Find the final volume of water in the cylinder
The difference in the final volume and initial volume of water is the volume of the solid
Chapter 4: Light [Energy]
Properties of light
Light travels in straight lines
Light can be reflected
How are shadows formed?
Light travels in straight lines
Hence, a shadow is formed when light is completely or partially blocked by an object
Sources of light:
The Sun
Lamps, light bulbs
Fireflies
Fuels
We can see an object when it reflects light into our eyes or when the object itself is a light source and give out light that enters our eyes.
Transparency of materials
Transparent | Allows most light to pass through | No shadow |
Translucent | Allows some light to pass through | Fainter shadow |
Opaque | Does not allow light to pass through | Dark shadow |
Size of shadow affected by source-object and object-screen
Distance between object and light source | Distance between object and screen | Effect on size of shadow | |
Greater | Closer | Smaller | |
Closer | Greater | Bigger | |
Size of shadow formed from an object in a vertical position (e.g. Lamp post)
Further away the object is from the light source, the longer the shadow
Below the light source -> shortest shadow
Light intensity
the further the distance between the light source and light sensor, the lower the light intensity
Units of light can go to zero when an opaque object blocks all light from reaching the sensor
Shape of shadows
When light is shone on different parts of an object, it can form shadows of different shapes
Chapter 5: Heat [Energy]
Heat is a form of energy.
It flows from a hotter to a colder object/ region/ place, until both reach the same temperature.
Amount of heat energy an object has depends on:
Mass of an object
Temperature
Common sources of heat:
The Sun
Fuels (we burn charcoal, petroleum, wood)
Electrical appliances
Temperature of an object is a measurement of its degree of hotness.
measure using a thermometer
datalogger with temperature/heat sensor can be used as well
*You can think of it this way:
Temperature is just a number to tell which object is hotter or colder
It suggest where the heat energy will flow to (hotter to colder object)
When heat flows from A to B:
A loses heat, B gains heat
temperature of A decreases, temperature of B increases
heat will stop flowing when both A and B reaches the same temperature
*Hence when heat flows (object gain or lose heat) -> temperature of object changes
Effects of heat gain/loss
When a matter (s/l/g) gains heat, it will expand (increase in volume).
When a matter (s/l/g) loses heat, it will contract (decrease in volume).
Heat gain/loss will result in change in state of matter:
From | To | Process | |
Heat gain | solid | liquid | melting |
liquid | gas | boiling/ evaporation | |
Heat loss | gas | liquid | condensation |
liquid | solid | freezing |
Good conductors of heat: materials that gain and lose heat at a faster rate
E.g. Metals
Poor conductors of heat: materials that gain and lose heat at a slower rate
E.g. Wood, plastics, air, rubber
Surface area and thickness will affect the rate of heat gain/loss as well.
Still need help with Primary 4 Science?If chemistry feels confusing or hard to follow, you’re not alone. At UpLabs Learning Centre, we explain concepts step by step so students can understand clearly — not just memorise. Our tutors are patient, supportive, and experienced with the school syllabus. We help students build confidence early and keep up in class. 👉 Try a lesson with UpLabs and make chemistry easier to understand. |
Comments