Year 6 · Chapter 2

Classifying living things

By the end of this chapter you will be able to

Sort living things into the broad groups of plants, animals and micro-organisms
Sort plants into flowering plants, conifers, ferns and mosses, using flowers, seeds and cones
Sort vertebrates into fish, amphibians, reptiles, birds and mammals, and recognise invertebrates
Describe micro-organisms, and explain why they need a microscope
Use a yes/no classification key to identify an animal, and write a new key question
Give reasons for a group, using specific characteristics

You should already know

Living things and their needs (Year 5 Science)
Fair tests and tables from Chapter 1 of this book

Where this leads

Classification in the Year 6 evolution and inheritance chapters, and in Key Stage 3 biology

National Curriculum for England, Key Stage 2 science, Year 6. Content: LH1 describe how living things are classified into broad groups by common observable characteristics, including micro-organisms, plants and animals, LH2 give reasons for classifying plants and animals based on specific characteristics.

Exercise P Do you remember?

FWhat is the young stage of a frog called? Write the word.

Done

FWhat is the name for an animal that eats only plants? Write the word.

Done

FWhich part of a plant takes in water from the soil? Write the word.

Done

FWhat covers a bird's body and helps it fly? Write the word.

Done

FWhich group of animals has a backbone? Write the word.

Done

2.1

Sorting living things into groups

Year 6
LH1: living things are classified into broad groups by common observable characteristics, including micro-organisms, plants and animals

Video lesson: Sorting living things into groupsComing soon

Story. Ruby and Mo are sorting cards of living things for a science display. Ruby says, “An oak tree goes with the daisy, and the snail goes with the dog.” Mo says, “Good, but what about the bacteria? They are too small to see.” Mr Patel says, “Scientists sort living things into broad groups. Let’s find the groups.”

Scientists classify living things by sorting them into groups. They use observable characteristics, which are features that can be seen, measured or tested. The three broad groups are:

plants, which make their own food using light;
animals, which cannot make their own food and must eat;
micro-organisms, which are living things too small to see clearly without a microscope.

A group is a set of living things with characteristics in common.

A tree diagram: living things split into plants, animals and micro-organisms. Animals split into those with a backbone and those without.

Key ideas

Living things are sorted into groups using observable characteristics.
The broad groups are plants, animals and micro-organisms.
Plants make their own food using light. Animals cannot make their own food.
Micro-organisms are living things too small to see clearly without a microscope.

Worked example 2.1.1

An oak tree is a living thing. Which broad group is it in: plants, animals or micro-organisms? Write the group.

Method. Think about how the oak makes its food.

Look at the feature. An oak tree makes its own food using light.
makes its own food
Choose the group. Living things that make their own food using light are plants.
plants
Write the answer.
plants

Check. An oak is a large plant, so it belongs with the daisy. ✓

Worked example 2.1.2

A snail moves about and eats leaves that it does not make. Which broad group is it in? Write the group.

Method. Think about whether it makes its own food.

Look at the feature. The snail cannot make its own food, so it must eat.
must eat
Choose the group. Living things that cannot make their own food and must eat are animals.
animals
Write the answer.
animals

Check. A snail is an animal, even though it eats plants. ✓

Watch out. An animal eats plants, but a plant does not eat animals.

Worked example 2.1.3

A bacterium is a living thing that is too small to see without a microscope. Which broad group is it in? Write the group.

Method. Think about its size.

Look at the size. It is too small to see clearly without a microscope.
too small
Choose the group. Living things too small to see clearly are micro-organisms.
micro-organisms
Write the answer.
micro-organisms

Check. Bacteria are micro-organisms. ✓

Watch out

Watch out: a living thing is not sorted by how big it is, or by its name. It is sorted by what it does and what it is made of, such as how it gets food.

Exam tip

Exam tip. Name the observable characteristic you used to sort a living thing, such as whether it makes its own food.

Try it (with your teacher, or a grown-up at home). Look at a bunch of living things at home or school: a houseplant, a pet, and a bowl of soil with small creatures you can see. Sort them into plants and animals. Ask: “Does it make its own food?” Do not touch wild creatures; watch them and wash your hands afterwards.

2.2

Plants

Year 6
LH1: living things are classified into broad groups by common observable characteristics, including plants, LH2: give reasons for classifying plants based on specific characteristics

Video lesson: PlantsComing soon

Story. Priya and Aisha go on a walk in the park and collect pictures of plants. “This oak has flowers and seeds,” says Priya. “This pine has cones, and this fern has no flowers at all,” says Aisha. “How do we group them?”

Plants are sorted by their characteristics, especially whether they make flowers and seeds.

Flowering plants make flowers, and their seeds form inside fruits or seed pods.
Conifers, such as pine trees, do not make flowers. They make seeds inside cones.
Ferns and mosses do not make flowers or seeds. They reproduce using tiny cells called spores.

Four plants: a flowering plant, a conifer with cones, a fern and a moss patch. Not to scale.

The table shows five plants and what each one makes.

Plant	What it makes	Group
Oak tree	flowers and seeds (acorns)	flowering plant
Daisy	flowers and seeds	flowering plant
Pine tree	cones with seeds, no flowers	conifer
Fern	no flowers, no seeds; spores	fern
Moss	no flowers, no seeds; spores	moss

Key ideas

Flowering plants make flowers and seeds.
Conifers make cones, and their seeds form inside the cones.
Ferns and mosses make no flowers and no seeds; they reproduce with spores.
Use flowers and seeds as the first characteristics when you sort plants.

Worked example 2.2.1

Look at the table in section 2.2. Which plant makes cones? Write the name.

Method. Find the plant that makes cones.

Read the column. The pine tree makes cones with seeds inside.
cones
Write the name. So the plant that makes cones is the pine tree.
Pine tree
Write the answer.
Pine tree

Check. Pine trees are conifers. ✓

Worked example 2.2.2

Look at the table in section 2.2. Which two plants have no flowers and no seeds? Write the two names.

Method. Find the plants that have no flowers and no seeds.

Read the table. The fern and the moss both have no flowers and no seeds.
no flowers, no seeds
Write the names. So the two plants are the fern and the moss.
Fern and Moss
Write the answer.
Fern and Moss

Check. Both reproduce using spores. ✓

Worked example 2.2.3

Is a daisy a flowering plant? Write yes or no, using the table in section 2.2.

Method. Check whether the daisy makes flowers.

Read the table. The table says the daisy makes flowers and seeds.
flowers and seeds
Decide. Because it makes flowers, the daisy is a flowering plant.
yes
Write the answer.
yes

Check. The oak tree also makes flowers and seeds. ✓

Watch out

Watch out: a tree is not always a flowering plant. A pine is a tree, but it makes cones, not flowers.

Exam tip

Exam tip. When you sort plants, look for flowers first, then seeds, cones or spores.

Try it (with your teacher, or a grown-up at home). Collect three different leaves from a garden or a park, with a grown-up's permission. Do not pick flowers or berries, and wash your hands. Sort the leaves into two groups: leaves from trees with flowers, and leaves from trees without flowers. Explain your reason.

2.3

Animals with and without a backbone

Year 6
LH1: living things are classified into broad groups by common observable characteristics, including animals, LH2: give reasons for classifying animals based on specific characteristics

Video lesson: Animals with and without a backboneComing soon

Story. A class visits a farm. Mo sees a hen, a cow, a frog in a pond and a spider in a corner. “Why is the frog in one group and the spider in another?” he asks. The farmer says, “Look for a backbone first.”

Animals are sorted into two big groups: those with a backbone and those without.

Animals with a backbone are vertebrates. These are fish, amphibians, reptiles, birds and mammals.
Animals without a backbone are invertebrates. Insects, spiders and worms are examples.

Each vertebrate group has its own characteristics, such as scales, feathers or hair. Invertebrate groups are sorted using features such as the number of legs.

Simple drawings of six animals: a fish, a frog, a lizard, a bird, a dog and an ant. Not to scale.

The table gives the characteristics of each group.

Group	What the group members have
Fish	live in water, have fins and gills, usually have scales
Amphibians	live on land and in water, have moist skin, usually lay eggs in water
Reptiles	have dry scaly skin, usually lay eggs with a leathery shell on land
Birds	have feathers and a beak, lay eggs with hard shells
Mammals	have hair or fur, most give birth to live young, feed their young on milk
Insects	have six legs and three body parts
Spiders	have eight legs and two body parts
Worms	have no legs and a soft body

A spider with eight legs and a worm with no legs. Neither has a backbone.

Key ideas

Vertebrates have a backbone: fish, amphibians, reptiles, birds and mammals.
Invertebrates have no backbone: insects, spiders and worms are examples.
Birds have feathers and beaks. Mammals have hair or fur and feed their young on milk.
Insects have six legs; spiders have eight legs; worms have no legs.

Worked example 2.3.1

Look at the table in section 2.3. Which group has feathers and a beak? Write the group.

Method. Find the group with feathers.

Read the table. The birds have feathers and a beak.
feathers and a beak
Write the group. So the group is birds.
birds
Write the answer.
birds

Check. Birds are vertebrates, because they have a backbone. ✓

Worked example 2.3.2

Look at the table in section 2.3. Which group has dry, scaly skin? Write the group.

Method. Find the group with dry, scaly skin.

Read the table. The reptiles have dry, scaly skin.
dry, scaly skin
Write the group. So the group is reptiles.
reptiles
Write the answer.
reptiles

Check. A snake and a lizard are both reptiles. ✓

Worked example 2.3.3

An ant has six legs and no backbone. Which invertebrate group is it in? Write the group.

Method. Find the invertebrate with six legs.

Read the table. The table says an insect has six legs and three body parts.
six legs
Write the group. So an ant is an insect.
insects
Write the answer.
insects

Check. An ant has six legs and no backbone, so it is an invertebrate. ✓

Watch out

Watch out: an animal that flies is not always a bird. A bird has feathers and a backbone, but an insect can fly and has no backbone.

Exam tip

Exam tip. Start with the backbone: if there is one, the animal is a vertebrate, and then use the other characteristics to name its group.

Try it (with your teacher, or a grown-up at home). Look at pictures of five animals from books or a safe website, with a grown-up. Write down whether each one has a backbone. Then say which group each vertebrate belongs to, using feathers, fur, scales or moist skin. Do not touch wild animals or insects.

2.4

Micro-organisms

Year 6
LH1: living things are classified into broad groups by common observable characteristics, including micro-organisms

Video lesson: Micro-organismsComing soon

Story. Tom looks at a drop of pond water under a microscope. “There are tiny living things moving about,” he says. “Are they animals?” Mrs Chen says, “They are micro-organisms, a group of their own.”

Micro-organisms are living things that are too small to see clearly without a microscope. Many micro-organisms are single-celled, which means each one is made of one cell.

Bacteria are single-celled micro-organisms. An amoeba is another single-celled micro-organism, found in pond water. Both move, grow and reproduce, which shows they are alive.

Pictures of micro-organisms are drawn much bigger than they really are, so that we can see their shapes.

A bacterium drawn as a rod and an amoeba drawn as a blob. Both are single-celled micro-organisms. Not to scale.

Key ideas

Micro-organisms are living things too small to see clearly without a microscope.
Many micro-organisms are single-celled, made of one cell.
Bacteria and amoebas are examples of micro-organisms.
Micro-organisms are a broad group of their own.

Worked example 2.4.1

Are micro-organisms too small to see clearly with the eye alone? Write yes or no.

Method. Use the definition of micro-organisms.

Read the definition. Micro-organisms are living things too small to see clearly without a microscope.
too small
Decide. So micro-organisms are too small to see clearly with the eye alone.
yes
Write the answer.
yes

Check. A microscope is needed to see them clearly. ✓

Worked example 2.4.2

What do we use to see a micro-organism clearly? Write the word.

Method. Think about what makes very small things bigger.

Read the idea. We need an instrument that makes very small things look larger.
larger
Name the instrument. That instrument is a microscope.
microscope
Write the answer.
microscope

Check. A magnifying glass is not strong enough for most micro-organisms. ✓

Worked example 2.4.3

Is an amoeba made of one cell? Write yes or no.

Method. Think about a single-celled micro-organism.

Read the description. An amoeba is a single-celled micro-organism.
single-celled
Decide. So an amoeba is made of one cell, and the answer is yes.
yes
Write the answer.
yes

Check. Bacteria and amoebas are both single-celled. ✓

Watch out

Watch out: micro-organisms are not plants. Many are not plants or animals, and they form a broad group of their own.

Exam tip

Exam tip. Use the word single-celled when you describe micro-organisms, and say that a microscope is needed to see them clearly.

Try it (with your teacher, or a grown-up at home). With a grown-up, look at a few drops of pond water or tap water under a classroom microscope, if one is available. Draw what you see, and count how many moving things you can see in one drop. Wash your hands afterwards. Do not taste or drink pond water.

2.5

Using a classification key

Year 6
LH2: give reasons for classifying plants and animals based on specific characteristics; use classification keys to identify living things

Video lesson: Using a classification keyComing soon

Story. A class has a bag of mystery creatures from the school field. Mr Patel gives them a key: a list of yes or no questions. “Answer each question, and follow the step,” he says. “The key will tell you the group.”

A classification key is a list of questions with only yes or no answers. Each answer sends you to the next step, until you reach the name of the group.

A key is useful because the questions are based on specific characteristics. Each question splits the living things into two smaller groups.

The key below starts with the backbone. Work down it, one step at a time.

Step	Question	If yes	If no
A	Does it have a backbone?	Go to step B.	Go to step I.
B	Does it have feathers?	It is a bird.	Go to step C.
C	Does it have fur or hair?	It is a mammal.	Go to step D.
D	Does it have fins and live in water?	It is a fish.	Go to step E.
E	Does it have dry, scaly skin?	It is a reptile.	It is an amphibian.
I	Does it have six legs?	It is an insect.	Go to step J.
J	Does it have eight legs?	It is a spider.	It is a worm.

Bar chart of 20 creatures sorted by a class: fish 3, amphibians 2, reptiles 2, birds 4, mammals 3, insects 3, spiders 2, worms 1.

The table below gives the characteristics of some organisms. Use it with the key.

Organism	backbone	feathers	fur or hair	scales	fins	legs
Salmon	yes	no	no	yes	yes	no
Frog	yes	no	no	no	no	yes
Lizard	yes	no	no	yes	no	yes
Robin	yes	yes	no	no	no	yes
Dog	yes	no	yes	no	no	yes
Earthworm	no	no	no	no	no	no
Ant	no	no	no	no	no	yes

Key ideas

A key is a list of yes or no questions that leads to a group.
Start with the first question, and follow the step that matches your answer.
Each question uses a specific characteristic, such as feathers or legs.
A new key question must split the group into two parts.

Worked example 2.5.1

Use the key in section 2.5. An animal has feathers. Which group is it in? Write the group.

Method. Start at step A, then go to step B.

Step A. The animal has a backbone, so go to step B.
backbone: yes
Step B. The animal has feathers, so it is a bird.
feathers: yes
Write the answer.
bird

Check. Feathers are a characteristic of birds only. ✓

Worked example 2.5.2

Use the key in section 2.5. An animal has a backbone, fur and no feathers. Which group is it in? Write the group.

Method. Work down the key.

Step A. It has a backbone, so go to step B.
backbone: yes
Step B. It has no feathers, so go to step C.
feathers: no
Step C. It has fur, so it is a mammal.
fur: yes
Write the answer.
mammal

Check. A dog follows the same path. ✓

Worked example 2.5.3

Use the key in section 2.5. An animal has six legs and no backbone. Which group is it in? Write the group.

Method. Start at the backbone question.

Step A. It has no backbone, so go to step I.
backbone: no
Step I. It has six legs, so it is an insect.
six legs: yes
Write the answer.
insect

Check. An ant has six legs and no backbone. ✓

Watch out. Check the first question carefully: a no answer to the backbone question takes you to a different part of the key.

Watch out

Watch out: a key only works if you answer every question honestly, and follow the step that matches your answer.

Exam tip

Exam tip. When you use a key, write down each question and your answer, so that you can check the route.

Try it (with your teacher, or a grown-up at home). Make a key with three yes or no questions to separate three objects in the classroom: for example, a pencil, a book and a cup. Give the key to a partner, and see whether they can name the objects. Keep the questions simple and about one characteristic at a time.

Chapter summary

Skill	Method
Broad groups	Living things are sorted into plants, animals and micro-organisms, using observable characteristics.
Plants	Flowering plants make flowers and seeds. Conifers make cones. Ferns and mosses reproduce with spores.
Animals	Vertebrates have a backbone: fish, amphibians, reptiles, birds and mammals. Invertebrates have no backbone.
Micro-organisms	Too small to see clearly without a microscope. Many are single-celled, such as bacteria and amoebas.
Keys	A key is a set of yes or no questions. Each answer leads to the next step, until the group is named.

Can you…?

I can sort living things into plants, animals and micro-organisms
I can use flowers, seeds, cones and spores to sort plants
I can name the five vertebrate groups, and two invertebrate groups
I can describe a micro-organism, and say why a microscope is needed
I can use a yes/no classification key to name a group
I can write a new key question, and give a reason for a group

Key terms

classify: to sort things into groups using their characteristics
observable characteristic: a feature that can be seen, measured or tested
micro-organism: a living thing too small to see clearly without a microscope
single-celled: made of one cell
vertebrate: an animal with a backbone
invertebrate: an animal without a backbone
conifer: a plant that makes cones and seeds, and no flowers, such as a pine tree
spore: a tiny cell that a fern or moss uses to reproduce
classification key: a list of yes or no questions that leads to the name of a group
amphibian: a vertebrate with moist skin that lives on land and in water, such as a frog

Total 17 marks. Allow about 17 minutes.

Exercise 2X Practice test questions

FWrite the three broad groups that living things are sorted into. Write the three words.[1 mark]

Done

FA flowering plant makes flowers and seeds. A pine tree makes cones and seeds. Write one characteristic that a pine tree does not share with a flowering plant. Write one word.[1 mark]

Done

FA fern has no flowers and no seeds. A moss has no flowers and no seeds. Write the name of the cells that ferns and mosses use to reproduce.[1 mark]

Done

PSA creature has a backbone, feathers and a beak, and lays eggs with hard shells. Write its group, using the key in section 2.5.[2 marks]

Done

PSA creature has no backbone and six legs. Write its group, using the key in section 2.5.[2 marks]

Done

FUse the table below. Write the name of the animal that has fins and scales.

Animal	Fins	Scales
Salmon	yes	yes
Robin	no	no
Dog	no	no

[1 mark]

Done

PSA class sorted 20 creatures: fish 3, amphibians 2, reptiles 2, birds 4, mammals 3, insects 3, spiders 2 and worms 1. Write the number of vertebrates in the sort.[2 marks]

Done

RA student says: “A bat is a bird because it has wings.” Explain why the student is not right. Write one sentence.[2 marks]

Done

RWrite one reason why a micro-organism is grouped separately from a plant, even though both are living things. Write one sentence.[2 marks]

Done

PSUse the key in section 2.5. A creature has a backbone, dry, scaly skin and no fins. Write its group.[3 marks]

Done

← Chapter 1: Working scientifically (Years 5-6)Chapter 3: The circulatory system and transport →

Classifying living things

By the end of this chapter you will be able to

You should already know

Where this leads

Exercise P Do you remember?

Sorting living things into groups

Key ideas

Watch out

Exam tip

Exercise 2A Sorting living things into groups

Plants

Key ideas

Watch out

Exam tip

Exercise 2B Plants

Animals with and without a backbone

Key ideas

Watch out

Exam tip

Exercise 2C Animals with and without a backbone

Micro-organisms

Key ideas

Watch out

Exam tip

Exercise 2D Micro-organisms

Using a classification key

Key ideas

Watch out

Exam tip

Exercise 2E Using a classification key

Chapter summary

Can you…?

Key terms

Exercise 2Z Check-up

Exercise 2X Practice test questions