P3 Science — Complete Summary Notes

TOPICClassifying Animals 🌍

Scientists have classified animals into many different groups. Here are the six common ones:

📋 All Animal Groups — Full Comparison

Group	Habitat	Outer Covering	Breathing	Reproduction	Body Temp	Backbone?
🐘 Mammals	Land & water 🌊	Hair or fur	Lungs	Most give birth to young alive	Warm-blooded	✅ Yes
🐦 Birds	Most on land	Feathers 🪶	Lungs	Lay eggs 🥚	Warm-blooded	✅ Yes
🐟 Fish	Water 🌊	Scales	Gills	Most lay eggs 🥚	Cold-blooded	✅ Yes
🐛 Insects	Most on land	Hard outer covering	Breathing holes	Most lay eggs 🥚	Cold-blooded	❌ No
🦎 Reptiles	Land & water 🌊	Dry skin with scales	Lungs	Most lay eggs 🥚	Cold-blooded	✅ Yes
🐸 Amphibians	Land & water 🌊	Moist skin	Lungs + moist skin	Lay eggs 🥚	Cold-blooded	✅ Yes

⭐Unique Characteristics

These are the key features that help you identify each group:

🐘 Mammals

Covered with hair or fur
Feed their young with milk 🍼

🐦 Birds

Covered with feathers 🪶
Have a beak

🐛 Insects

Three body parts: head, thorax and abdomen
Six legs attached to the thorax

TOPICClassifying Plants 🌍

Plants can be placed into groups based on their characteristics. Here are the ways we classify them:

🌸Flowering or Non-Flowering

Flowering plants, such as the hibiscus and rose, bear flowers when fully grown.
Non-flowering plants, such as ferns and mosses, do not bear flowers.

🌱Seed-Bearing or Spore-Bearing

Plants may reproduce by seeds or spores.
Seeds and spores can develop into a new plant, allowing the plant to ensure the continuity of its own kind.

📋Key Takeaway — Flowering vs Non-Flowering Plants

	🌸 Flowering Plants	🌿 Non-Flowering Plants
Reproduction	By seeds 🌱	By spores 🍂
Making Food	Both make their own food through photosynthesis ☀️🌿

📋Classifying Plants — By Habitat, Safety & Appearance

By	Category	Detail / Example
Habitat	Land plants	Grow on land (e.g. trees, grass)
	Floating water plants	Rest on the surface of the water
	Partially-submerged	Roots underwater, leaves/flowers above water
	Fully-submerged	Completely underwater
Safety	Poisonous	Harmful if handled or consumed (itchiness, rashes, blindness, death)
Safety	Non-poisonous	Grown for food — e.g. carrot root, potato stem
Flowers	Grow singly or in clusters
Fruits	By seeds	One seed (mango) vs. many seeds (watermelon)
	By skin texture	Smooth (papaya) vs. rough/hairy (kiwi)
	By edibility	Eatable (tomato) vs. inedible (pong pong)
Stems	Strong stems	Hold themselves upright
Stems	Weak stems	Cling to other plants or crawl along the ground
Leaves	By shape	Heart-shaped, oval-shaped, palm-shaped, lance-shaped
	By edges	Jagged-edged or smooth-edged
	By vein pattern	Net veins or parallel veins

TOPICFungi 🍄

Fungi come in different shapes and sizes. Examples include mushrooms, moulds, and yeasts.

📋Fungi — Key Characteristics

Feature	Detail
Food	Obtain food from other dead or living things (cannot make their own)
Reproduction	By spores 🍂
Growth needs	Warmth, air, moisture — prefer dark places
Movement	Cannot move by themselves (like plants)

⭐Types of Fungi

🍄 Mushrooms

Spores found under the cap in the gills
Examples: button mushroom, truffle

🟢 Moulds

Spores in a spore bag at the end of the stalk
Grow in warmth, moisture, and air
Prefer dark places

🍞 Yeasts

Used to make food such as bread
Single-celled fungi

TOPICBacteria 🦠

Bacteria can be found everywhere. They have different shapes and sizes, but they are so small that they can only be seen using a microscope — making them micro-organisms.

📋Bacteria — Key Characteristics

Feature	Detail
Size	Can only be seen with a microscope (micro-organisms)
Food	Obtain food from other dead or living things (cannot make their own)
Survival needs	Air, food, and water — like all living things
Growth	Warm conditions increase bacteria growth

⚖️Bacteria — Useful or Harmful?

	✅ Useful	❌ Harmful
Digestion	Help us digest food	Cause us to fall sick (e.g., from unwashed hands)
Food production	Making cheese and yoghurt	Cause us to fall sick (e.g., from unwashed hands)
Medicine	Making medicine such as insulin	Cause decay and food spoilage
Nature	Break down dead plants and animals into simpler substances (like fungi)	Cause decay and food spoilage

TOPICFungi vs Bacteria — Side by Side 🔄

Fungi and bacteria share some similarities but also have important differences:

	🍄 Fungi	🦠 Bacteria
Food	Both obtain food from other dead or living things (cannot make their own)
Reproduction	By spores	By splitting into two
Size	Some visible to naked eye (mushrooms)	Only visible with a microscope
Growth needs	Both need warmth, air, and moisture
Movement	Neither can move by themselves from place to place
Nature role	Both break down dead plants and animals into simpler substances

TOPICPhysical Properties of Materials

💡 Exam Tip!

Memorise the 5 properties of materials using S-T-A-F-F:

S — Strength
T — Transparency
A — Absorbency
F — Flexibility
F — Float on water? (Buoyancy)

📋 Summary of Properties

Property	Definition
Strength	Ability to withstand heavy loads without breaking or tearing
Transparency	Ability to allow light to pass through Transparent: Most light can pass through Translucent: Some light can pass through Opaque: No light can pass through
Absorbency	Ability to soak up liquid A material that cannot absorb any liquid is waterproof
Flexibility	Ability to bend without breaking or tearing The more flexible a material, the more it bends when the same force is applied
Float on water? (Buoyancy)	Determines if a material floats or sinks in water A material denser than water will sink, regardless of mass

🎯 Choosing the Most Suitable Material

Set-up 1: Which material is best for making a bag?

Step	Answer
Material chosen	Material X
Results	It could hold the most weights without breaking
Property shown	It is the strongest material
Function of object	A bag needs to carry heavy loads without breaking or tearing

TOPICLife Cycles of Plants

What Are Life Cycles?

Plants reproduce to ensure the continuity of their own kind.
Most plants reproduce by seeds. Of these plants, most are flowering, but some, like firs and pines, are non-flowering and store their seeds in cones instead.
Some plants, however, reproduce by spores. These plants include ferns and mosses.

Flowering Plants

Plants that reproduce by seeds are called flowering plants.

🌰 Seed Germinates into a new plant under the right conditions

🌱 Young Plant (Seedling) Leaves, stem and roots develop

🌻 Adult Plant Develops flowers and fruits

Germination

For most seeds, the basic conditions needed for germination are:

💧 Water

🌬️ Air (Oxygen)

☀️ Warmth

💡 Seeds do NOT need light to germinate because they don't have leaves yet to capture sunlight. Instead, seeds use the food stored in their seed leaves for energy during this early stage of growth.

Parts of a Seed

🛡️ Seed Coat A thin outer layer that protects the seed.

🌾 Seed Leaf It provides the seedling with stored food for growth before the seedling grows true leaves to trap light to make its own food.

🌱 Root (Embryonic) First to grow during germination, absorbs water for the plant to grow.

Growth

When a seed germinates, the root appears first, followed by the shoot (consisting of the leaves and stem).
During the initial stages of development, the seedling obtains food from the seed leaves.
Once the leaves emerge, however, the seedling can make its own food.
When all the stored food in the seed leaves is used up, the seedling depends solely on its leaves to trap light and make food.

🌰 Seed Dormant, waiting for the right conditions to begin growth.

🌱 Root Emerges Germination begins — the root grows first and absorbs water.

🪴 Shoot Grows The seed leaf provides stored food for the growing seedling.

🌿 True Leaves The plant can now make its own food through photosynthesis.

Adult Plants

The plant is at the adult stage when it starts to produce flowers and bear fruits.
The fruits contain seeds which will grow into new plants.

TOPIC What is a Life Cycle?

Animals have life cycles as it ensures the continuity of their own kind.
A life cycle has no starting or ending point.

🥚 Eggs

This increases the chances of the eggs hatching and the young surviving to adulthood to reproduce and continue the life cycle.

🏠 Habitat

Some animals spend their life cycle entirely on land while others spend it partly in water.

👁 Appearance

In three-staged life cycles, the young animal resembles the adult.
In four-staged life cycles, the young animal does not resemble the adult.

🎯 Number of Stages

Animals can have a different number of stages in their life cycles.
Most animals have three stages in their life cycles, while others have four stages in their life cycles.

📌

Exam Tip! Use the acronym HAS — Habitat, Appearance, Stages — to compare life cycles.

TOPIC Three-Staged Life Cycles

🥚 Egg

→

🐣 Young
(Nymph)

→

🐥 Adult

🐤 Chicken	🐸 Frog	🐜 Cockroach	🦗 Grasshopper
Life cycle takes place entirely on land	Life cycle takes place partly in water	Life cycle takes place entirely on land	Life cycle takes place entirely on land
Young resembles the adult	Young does not resemble the adult	Young resembles the adult	Young resembles the adult

🦗 Insects with Three Stages

The young of an insect with a three-staged life cycle is known as a nymph.
To develop from a nymph to an adult, an insect undergoes moulting.

An insect moults to shed its hard outer covering in order to grow bigger.

Nymph	Adult
Does not have wings	Has wings
Cannot fly	Can fly
Undergoes moulting	Does not moult
Cannot reproduce	Can reproduce

TOPIC Four-Staged Life Cycles

🥚 Egg

→

🐛 Larva

→

Pupa

→

🦋 Adult

Animals such as the mosquito, mealworm beetle and the butterfly have life cycles that consist of four basic stages — egg, larva, pupa and adult.
Insects with four-staged life cycles undergo moulting in the larval stage.

In the larval stage, the animal feeds the most as it grows in size.
Once the larva has grown fully, it enters the pupal stage, in which the animal does not feed.

During the pupal stage, the insect undergoes a drastic change in its appearance to become an adult.
All animals with four-staged life cycles have young that do not resemble the adult.

🦋 Butterfly vs. Mosquito

🦋 Butterfly	🦟 Mosquito
Life cycle takes place entirely on land	Life cycle takes place partly in water
Young does not resemble the adult	Young does not resemble the adult
Considered a pest in larval stage as it feeds on large amounts of leaves, causing damage to plants.	Considered a pest in adult stage as female mosquitoes feed on human blood and can spread diseases such as dengue.

🛠 Mosquito Control

The female mosquitoes lay their eggs in stagnant water.
Mosquitoes are the easiest to eliminate in the egg, larval and pupal stages as they cannot fly.

Spraying oil on the surface of the water blocks the breathing tubes of the larva and pupa of the mosquito and prevents them from taking in oxygen.
It is most difficult to kill mosquitoes in the adult stage as they can fly and escape easily.

TOPICMagnets

🧲 Types of Magnets

Naturally-occurring magnets are known as lodestones.
Magnets can be made of iron or steel. They come in many shapes and sizes.
- Some examples are bar magnets, U-shaped magnets and ring magnets.

⚡ Properties of Magnets

Magnets attract objects made of magnetic materials.
- Magnets exert a magnetic force of attraction on magnetic materials, such as iron and steel.
- Other materials, such as wood, plastic, glass, aluminium and copper, are not attracted to magnets and are known as non-magnetic materials.

💪 Magnetic Strength

The poles of a magnet have the greatest magnetic strength.
Bar magnet — poles are at the ends.
Ring magnet — poles are at the top and bottom surfaces.

The poles of a bar magnet are at the ends of the magnet.

🔄 Attraction and Repulsion

Unlike poles of magnets attract, while like poles repel.
- Every magnet has two poles: the north-seeking pole and the south-seeking pole.
- Magnets can interact with one another by either attracting (pulling) or repelling (pushing) each other.
- When the unlike poles of two magnets are facing each other (N - S), the two magnets will attract and move towards each other.
- When the like poles of two magnets are facing each other (N - N or S - S), the two magnets will repel and move away from each other.

📝 Common Question: Arrangements of magnets

The diagram below shows the arrangements of three bar magnets.

Not possible (N-N repel) Possible (unlike poles attract)

Arrangement A is not possible as the like poles of two magnets (N - N) are facing each other. Hence the magnets would repel.
Arrangement B is possible as the unlike poles of two magnets are facing each other. Hence the magnets would attract.

Investigating if an object is a magnet, made of a non-magnetic material or made of a magnetic material

The observations are recorded in the table below.

Metal bar	Observations (North-seeking pole and X)	Observations (North-seeking pole and Y)
A	Did not move	Did not move
B	X moved away from the magnet	Y moved towards the magnet
C	X moved towards the magnet	Y moved towards the magnet

Both ends of Metal bar A did not move, indicating that they were neither attracted to nor repelled by the bar magnet. Hence, Metal bar A is made of a non-magnetic material.
End X of Metal bar B moved away from the north-seeking pole of the magnet, indicating that they repelled each other. Since only magnets can repel another magnet when their like poles face each other, Metal bar B must be a magnet.
Both ends of Metal bar C moved towards the magnet, indicating that both ends were attracted to the magnet. Hence, Metal bar C is made of a magnetic material.

TOPICMaking a Temporary Magnet

🔧 Making a Temporary Magnet

The Stroke Method

An object made of a magnetic material, such as iron or steel, can be magnetised by stroking its entire length several times with the same pole of a magnet in one direction.
- The end of the object where the pole of the magnet first touches will be the same polarity as the pole of the magnet.

Factors that affect magnetic strength

The greater the number of strokes along the magnetic object, the greater the magnetic strength of the temporary magnet.
The greater the magnetic strength of the permanent magnet used to stroke the magnetic object, the greater the magnetic strength of the temporary magnet.

The Electrical Method

An object made of magnetic material, such as iron or steel, becomes magnetised when it is placed inside a coil of wire and an electric current is passed through the coil.
This type of magnet is called an electromagnet.

Factors that affect magnetic strength

The greater the number of coils of wire around the magnetic object, the greater the magnetic strength of the electromagnet.
The greater the number of batteries used, the greater the magnetic strength of the electromagnet.

🔥 Losing Magnetic Strength

A magnet can lose its magnetic strength when it is:

Heated over a strong flame
Dropped repeatedly
Hammered repeatedly

📝 Exam Tip

Remember:

Magnetic materials: Iron, steel (attracted to magnets)
Non-magnetic materials: Wood, plastic, glass, aluminium, copper (not attracted to magnets)
Unlike poles attract (N-S), like poles repel (N-N or S-S)
Only magnets can repel another magnet when their like poles face each other — magnetic materials are always attracted
A freely suspended or a freely floating magnet will always come to rest in the North-South direction