Chapter 1: Diversity of Living and Non-living Things | P3 Science
Chapter 1 · Primary 3 Science
Diversity of Living and
Non-living Things
📚 Section A — Revision Notes

🎯 What I Will Learn

  • What is diversity?
  • What is classification?
  • How can we show classification?
  • What are living and non-living things?
  • What do living things need to stay alive?
  • What are some other characteristics of living things?
1
What Is Diversity?
  • There are many things around us. Some are living things. Others are non-living things.
  • Diversity refers to the great variety of living things and non-living things around us.
  • We classify the diversity of things around us to understand them better.
2
What Is Classification?
  • Putting things into groups is called classification.
  • We can classify things based on their features, also known as characteristics. Examples: size, shape and colour.
  • Things with similar characteristics are placed in the same group.
  • The same things can be classified in many different ways.
Similarities — characteristics that two or more things have in common.
E.g. A bird and a bee both have wings. This is a similarity.
Differences — characteristics that two or more things do not have in common.
E.g. A bird has two legs, but a bee has six legs. This is a difference.
  • Classification helps us understand and study the diversity of things around us better.
  • Classification helps us organise things and show their similarities and differences clearly.
3
How Can We Show Classification?
  • We can show classification in different ways: using pictures, tables or graphic organisers.
Animals classified by number of legs Three columns: no legs (snake), two legs (penguin), four legs (cat) No legs Two legs Four legs Snake Penguin Cat
Animals with no legs Animals with two legs Animals with four legs
Snake Ostrich Elephant
Fish Penguin Cat
  • A flow chart is a common graphic organiser.
  • In a flow chart, each ◇ diamond shape has a Yes/No question. The answers help us classify things.
Animals Do they have legs? No Snake Fish Yes Do they have two legs? No Elephant Cat Yes Ostrich · Penguin
💡
Exam Tip — Reading Flow Charts
  • If the question says ‘Based on the flow chart’, use only the information from the flow chart. Do not use outside knowledge.
  • Example: If asked for a similarity between elephant and ostrich based on the flow chart above, the answer is “Both have legs” — not “Both are animals” (not shown in the chart).
  • To check your answer: write the names into the flow chart and trace through each question.
⚙️ Worked Example 1.1 — Flow Chart (P, Q, R)
Flow chart: Living things → Can it move from one place to another?
  • No → P
  • Yes → Can it fly?
    • No → Q
    • Yes → R

Which best represents P, Q and R from: Crow, Grass, Snail?
How to solve:
P cannot move → Grass (plants cannot move from place to place).
Q can move but cannot fly → Snail.
R can move and can fly → Crow.

Answer: P = Grass, Q = Snail, R = Crow → Option (3)
4
What Are Living and Non-living Things?
  • We can classify things around us into living things and non-living things.
  • Living things are things that are alive. (e.g. tree, cat, human)
  • Non-living things are things that are not alive. (e.g. cup, clock, chair)
  • Living things and non-living things are found all around us.
  • Some objects contain both — e.g. a potted plant: the plant (living) sits in a pot (non-living).
Living and non-living things Left shows living things: tree, cat, girl. Right shows non-living things: cup, clock, chair. ✓ Living things ✗ Non-living things Tree Cat Girl Cup Clock Chair
5
What Do Living Things Need to Stay Alive?
  • Living things need air, water and food to stay alive.
  • If living things do not have air, water or food, they will die.
💨 Air
  • Living things need air to stay alive. Air contains oxygen.
  • Animals that live on land breathe in air from their surroundings.
  • Animals that live in water have special body parts to help them get air (e.g. fish use gills).
  • Plants also need air to stay alive.
🎯
Get It Right!
✗ Wrong Animals that live in water, such as fish, do not need air.
✓ Correct Fish are living things, and all living things need air. Fish have special body parts called gills to help them get air from the water they live in.
👍
Good to Know
Divers who go into the deep sea need to carry oxygen tanks with them. The oxygen tank allows them to breathe underwater.
💧 Water
  • Living things need water to stay alive.
  • We need water to digest food, remove waste from our body and carry out daily activities.
  • Plants need water to make food. Without water, plants will die.
👍
Good to Know
We need to drink enough water every day. Not drinking enough water can harm our body. When we exercise, we sweat and lose water — that is why we feel thirsty.
🍎 Food
  • Living things need food to stay alive.
  • Food gives living things energy. Food also helps living things grow.
  • Animals eat food.
  • Plants do not eat food. They make their own food when they get air, water and light.
🎯
Get It Right!
✗ Wrong Plants get food from the soil.
✓ Correct Plants do not get food from the soil. They get water and minerals from the soil. They make their own food when there is light.
👍
Good to Know
Animals only eat food that is suitable for them. Not all animals will eat all types of food. Cows eat plants only; tigers eat meat only. If a cow is given meat, it cannot survive.
📋 Checkpoint 1.1
1. Name three things that living things need to stay alive.
Living things need air, water and food to stay alive.
⚙️ Worked Example 1.2 — Grasshopper in Jars
Four set-ups, each a glass jar with a grasshopper and leaves:
  • Set-up A: Water in bowl + leaves + lid with holes
  • Set-up B: Water + leaves + lid without holes (no air)
  • Set-up C: Leaves only + lid without holes (no air, no water)
  • Set-up D: Water + lid with holes (no food)

Q: In which set-up will the grasshopper still be alive after one week?
Grasshopper jar experiment — four set-ups Set-up A has water, leaves and lid with holes — grasshopper stays alive. Set-ups B, C and D are missing one need each, so the grasshopper dies. Set-up A ✓ Air ✓ Water ✓ Food ALIVE ✓ no holes Set-up B ✗ Air ✓ Water ✓ Food DIES ✗ no holes Set-up C ✗ Air ✗ Water ✓ Food DIES ✗ Set-up D ✓ Air ✓ Water ✗ Food DIES ✗ Which set-up will keep the grasshopper alive after one week? = hole in lid (air gets in) = solid lid (no air)
Answer: Set-up A.
Set-up A has water, food (leaves) and air (holes in lid). The grasshopper is a living thing — it needs all three to stay alive.
6
What Are Some Other Characteristics of Living Things?
  • Living things have many characteristics. Some make them different from non-living things.
📈
They can Grow
Become bigger and more complex
👁️
They can Respond
React to changes around them
🐣
They can Reproduce
Have young; ensure survival of their kind
📈 Living things can grow
  • Living things can grow. They become bigger in size.
  • Living things also become more complex as they grow — they may develop new body parts. (e.g. tadpole grows legs as it becomes a frog)
  • Animals use the food they eat to grow. Plants use the food they make to grow.
Tadpole grows into a frog Three stages showing a tadpole growing into a frog, with legs appearing at each stage. Stage 1 Stage 2 Stage 3 grows! grows! Tadpole Tadpole with legs Frog Living things grow bigger and become more complex over time.
👁️ Living things can respond to changes
  • Living things can respond to changes around them.
  • Examples of animals responding: A millipede curls up when touched. A boy covers his ears when music is loud.
  • Plants also respond: plants bend towards sunlight to make food. The mimosa plant (touch-me-not) closes its leaves when touched.
🎯
Get It Right!
✗ Wrong Plants are non-living things because they do not move.
✓ Correct Plants are living things. They do not move from place to place, but they move to respond to changes around them.
Plants respond to changes Left: a potted plant bending towards sunlight. Right: a mimosa plant closing its leaves when touched. Plant bends towards sunlight Mimosa closes when touched bends towards light Plants bend towards sunlight to make food. touch! leaves close! Mimosa (touch-me-not) closes its leaves when touched.
🐣 Living things can reproduce
  • Living things can reproduce — this means they can have young.
  • Living things reproduce to ensure the survival of their kind.
  • If living things do not reproduce, they would become extinct (no more of their kind).
  • Some animals reproduce by giving birth (e.g. cats, dogs). Some reproduce by laying eggs (e.g. chickens, fish, frogs).
  • Some plants reproduce through seeds. Some reproduce through spores.
Living things can reproduce Some animals give birth Some animals lay eggs A cat gives birth to kittens. A chicken lays eggs. The eggs hatch into chicks.
🎯
Get It Right!
✗ Wrong Seeds are non-living things.
✓ Correct Seeds are living things. Under the right conditions, they grow into plants, which are living things.
🎯
Get It Right!
✗ Wrong Everything that moves is a living thing.
✓ Correct Not everything that moves is a living thing. Living things move by themselves. Non-living things (like toy robots) move with the help of batteries — remove the batteries and they stop.
📊 Living vs Non-living Things
Living Things ✔ Non-living Things ✗
✔Need air, water and food ✗Do not need air, water and food
✔Grow ✗Do not grow
✔Respond to changes ✗Do not respond to changes
✔Reproduce ✗Do not reproduce
💡 Memory Trick — Mnemonic
Ned’s Grandma Repairs Rockets!
N
Need air, water & food
G
Grow
R
Respond to changes
R
Reproduce
💡
Exam Tip — Answer Phrasing
When asked for a characteristic of living things, always state it as a characteristic, not as what the animal did.

Question: A pangolin curls into a ball when attacked. Which characteristic of living things does this show?

✗ Do NOT say: “A pangolin responds to changes.”
✓ Correct: “Living things can respond to changes.”

Follow the phrasing in the question exactly.
📋 Checkpoint 1.2
1. State four characteristics of living things.
1. Living things need air, water and food to stay alive.
2. Living things can grow.
3. Living things can respond to changes.
4. Living things can reproduce.

⚡ Chapter Summary

  • Diversity = great variety of living and non-living things around us.
  • Classification = putting things into groups based on characteristics.
  • Classification can be shown using pictures, tables, and flow charts.
  • Living things are alive; non-living things are not alive.
  • Living things need air, water and food to stay alive.
  • Living things can grow, respond to changes, and reproduce.
  • Mnemonic: Ned’s Grandma Repairs Rockets! (N-G-R-R)

✏️ Test Yourself

1. It had not rained for a month. The grass behind Fiza’s school died. Which characteristic of living things does this show?
  • 1Living things need air to stay alive.
  • 2Living things need soil to stay alive.
  • 3Living things need light to stay alive.
  • 4Living things need water to stay alive.
2. Ali adopted a cat. After a few years the cat grew from 2 kg to 5 kg.

(a) Which characteristic of living things did the cat show?
Living things can grow.
(b) State one other characteristic of living things. (Do not repeat your answer from part (a).)
Accept any one of the following:
• Living things need air, water and food to stay alive.
• Living things can respond to changes.
• Living things can reproduce.
✏️ Test Yourself — Take the Chapter 1 Quiz →

15 questions · Instant feedback · Scores tracked by topic

P3 Science Chapter 1 — psle.edu.sg

Classifications of Living and Non-living Things

A) Living Things

The world around us is filled with a wide variety of things. Some can move, grow, and respond to their surroundings, while others cannot. To help us understand and study them more easily, we classify everything into two main groups — living things and non-living things.
Living things, such as humans, animals, and plants, have life. They can breathe, grow, reproduce, and respond to changes around them.
Non-living things, like rocks, water, and chairs, do not have life. They cannot move on their own, grow, or reproduce.
By grouping things this way, scientists can better study their similarities and differences and understand how living things depend on non-living things to survive.

All living things share certain characteristics that make them different from non-living things. Living things can grow and change as they get older. They can also respond to their surroundings — for example, animals run away from danger, and plants turn towards sunlight. Living things can reproduce, meaning they can produce young or new plants. They can move on their own, even if the movement is slow, like in plants. All living things will eventually die one day. To stay alive, they need air (oxygen), water, and food to get energy for important life processes such as respiration.

📘 For easy recall
Characteristics of Living Things:
🌱 They can grow.
👂 They can respond to changes around them.
👶 They can reproduce (produce offspring).
🚶 They can move by themselves.
⚰️ They can die eventually.
💧 They need air (oxygen), water, and food to get energy for life processes such as respiration.

Some Examples:

🌱 1. Growth
A bean seed is planted in a pot and watered daily. After a few days, a small shoot appears and slowly grows taller each day. This shows that living things can grow and change as they develop.

🐱 2. Movement and Reproduction
A mother cat gives birth to four kittens. When she hears a loud noise, she quickly carries her kittens to a quiet corner. This shows that living things can reproduce and move by themselves.

🐟 3. Need for Air, Water, and Food
A goldfish kept in a tank is fed daily and breathes through its gills in the water. When the water is not changed for many days, the fish becomes weak and may die. This shows that living things need air, water, and food to stay alive.

B) Classification of Living Things

Living things are classified into four main groups — plants, animals, fungi, and bacteria. Each group has unique features that help scientists study and understand how different living things grow, feed, and interact with their surroundings.

Classification of living things

  • Plants

  • Animals

  • Fungi

  • Bacteria

🌿 Plants

Plants are living things that can make their own food using sunlight, air, and water through a process called photosynthesis.
Most plants have roots, stems, and leaves, and they cannot move from place to place.
Plants also grow, respond to light, and reproduce to make new plants.

Examples include grass, mango trees, sunflowers, ferns, and seaweed.

🐾 Animals

Animals are living things that cannot make their own food. They get energy by eating plants or other animals.
Most animals can move on their own, respond to their surroundings, grow, and reproduce.
They also need air, water, and food to stay alive.

Examples include cats, birds, fish, frogs, and humans.

🍄 Fungi

Fungi are living things that cannot make their own food. They get nutrients by feeding on dead plants, animals, or waste materials.
Fungi do not have roots, stems, or leaves. Some fungi are large, like mushrooms, while others are so small that they can only be seen with a microscope.
Fungi play an important role in nature by breaking down dead matter and returning nutrients to the soil.

Common examples include mould, yeast, and mushrooms.

🦠 Bacteria

Bacteria are tiny living things made up of only one cell.
They are found almost everywhere — in the air, water, soil, and even inside our bodies.
Some bacteria are useful, such as those that help in digestion or making yoghurt, while others can cause diseases.
Bacteria can reproduce quickly when conditions are right.
Because they are so small, bacteria can only be seen under a microscope.

Examples of Bacteria
Lactobacillus – found in yoghurt and helps turn milk into yoghurt.
Escherichia coli (E. coli) – some types help in digestion in our intestines, but others can cause food poisoning.
Streptococcus – can cause sore throat or tooth decay.
Rhizobium – lives in soil and helps plants take in nitrogen for growth.

C) Classification of Plants


1. Plants are found everywhere around us and come in many different shapes, sizes, and colours.

2. They can grow in various places such as gardens, fields, ponds, walls, or even on other plants.

3. To grow well, plants need air, water, sunlight, and minerals.

4. Most plants have roots, stems, leaves, flowers, and fruits that help them to live, grow, and reproduce.

5. Flowering plants (e.g. apple tree, balsam plant) have flowers and fruits.

6. Non-flowering plants (e.g. fern) do not have flowers or fruits.

7. Ferns are non-flowering plants that reproduce through spores.

8. Plants can be classified based on their characteristics:
– Flowering plants (e.g. sunflower, mango) and non-flowering plants (e.g. bird’s nest fern, moss)
– Land plants (e.g. dumb cane, cactus) and water plants (e.g. cabomba, tape grass)
– Floating plants (e.g. duckweed, water lettuce), partially submerged plants (e.g. lotus, cattail), and fully submerged plants (e.g. hydrilla, cabomba)

9. Flowering plants can bear fruits with seeds.

D) Classification of Animals

1. There is a wide variety of animals around us, and they differ in many ways such as size, shape, and colour.

2. Animals can be classified based on observable characteristics such as their body covering, movement, and how they breathe, reproduce or the food they eat


Animals Live

(i) on land
(ii) in water


Animals Breathe

(i) through lungs
(ii) through gills


Animals reproduce by

(i) laying eggs
(ii) giving birth to live young


Animals eat

(i) plants only
(ii) both plants and animals
(iii) animals only

6 main groups of Animals

Mammals

– Have hair or fur on their bodies

– Give birth to live young with exception of platypus and spiny anteater

– Have babies that feed on the mother’s milk

– Breathe in air through lungs

Birds

– Have feathers on their bodies

– Have a beak , pair of wings and a pair of legs

– Lay eggs

– Breathe in air through lungs



Fish

– Have scales on their bodies

– Live in water

– Have fins for swimming

– Breathe through their gills in water

– Most lay eggs


Insects

– Have an external skeleton

– Have 6 legs and 2 antennae

– Hove bodies divided into 3 parts: the head,
thorax and abdomen

– Lay eggs

Reptiles

– Have scales on their bodies

– Breathe in air through lungs

– Most lay eggs







Amphibians

– Have outer coverings of moist skin

– Can live on land and in water

– Lay eggs


– Breathe through moist skin in water and through lungs on land

E) Fungi


Fungi – Key Facts at a Glance

Moulds and mushrooms are living things that help break down dead matter.

1
Living things
Fungi (e.g. mould, mushrooms) are living organisms that need air (oxygen), water and food to stay alive.
2
Not plants
Fungi do not have chlorophyll and cannot photosynthesise, so they cannot make their own food like plants.
3
Getting food
Fungi absorb nutrients from the surface they grow on, such as living tissues or dead plant and animal matter.
4
Decomposers
Many fungi are decomposers. They break down dead plants and animals into simpler substances in a process called decomposition.
5
Reproduction
Fungi reproduce by producing spores, which can grow into new fungi under suitable conditions.
6
Spore dispersal
Spores are tiny and very light, so they can be carried by the wind and spread over a wide area.
7
Real-life example
Keeping shoes dry (e.g. air them or blow to remove moisture) helps to prevent fungi from growing inside.
Remember: fungi need air, water and food — keep things dry and clean to slow their growth.
F) Bacteria

Bacteria – Tiny Helpers and Harmers

Microscopic living things found almost everywhere around us.

1
Microorganisms
Some living things are so tiny that we need a microscope to see them. These very small living things are called microorganisms.
2
Bacteria basics
Bacteria (one: bacterium) are microorganisms found almost everywhere. They need air (oxygen), water and food to stay alive.
3
Decomposers
Like fungi, many bacteria act as decomposers. They break down dead plants and animals into simpler substances.
4
Two sides
Bacteria can be useful or harmful depending on how they affect living things.
5
Helpful bacteria
Some bacteria help to make yoghurt, sour cream and cheese and are used in fermentation. Bacteria in our intestines aid digestion and support the removal of toxins from the body.
6
Harmful bacteria
Some bacteria cause illnesses such as diarrhoea, flu and food poisoning.
7
Staying safe
We cook food and boil water so they are safe to eat and drink. High temperatures reduce the number of bacteria and slow down how quickly they multiply.
Tiny but powerful: bacteria can help us, harm us, and play a big role in breaking down dead matter.
C) Classification of Non-Living Things

Non-living things can be grouped into once alive and never alive.
Those that were once alive come from living things, like wood or shells.
Those that were never alive come from the ground, like rocks, water, and metals.

  • Once Alive
  • never alive

Non-living things that were once alive come from living organisms that have died. They no longer show characteristics of life but still come from natural sources. Examples include wood from trees, shells from sea animals, and coal formed from ancient plants.

  • Occur Naturally
  • Man-made

Here are five examples of non-living things that were once alive and occur naturally:
Wood – comes from trees that were once living plants.
Coal – formed from the remains of ancient plants buried underground for millions of years.
Fossils – preserved remains or impressions of plants or animals that once lived long ago.
Shells – once part of living sea animals like snails or clams.
Amber – hardened tree resin that once flowed from living trees.

Non-living things that were once alive and man-made come from materials that used to be part of living organisms but have been changed or processed by humans. Examples include wooden furniture, paper made from trees, and leather bags made from animal skin.

Non-living things that were never alive do not come from living organisms. They are formed naturally from the Earth’s materials and have never shown any signs of life. Examples include rocks, water, air, metals, and sand. These make up much of our natural environment.

  • Occur naturally
  • Man-made

Non-living things that were never alive and occur naturally are formed from the Earth’s materials and have never come from living organisms. Examples include rocks, water, air, minerals, and sand. These things exist in nature and make up our planet’s physical environment.

Non-living things that were never alive and man-made are created by humans using materials that do not come from living organisms. They are usually made in factories or workshops. Examples include plastic bottles, glass windows, metal spoons, and cement bricks.

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