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Primary English · Year 5Chapter 2 · Prefixes: in-, dis-, de-, re-, auto- and bi-
Year 5 · Chapter 2

Prefixes: in-, dis-, de-, re-, auto- and bi-

By the end of this chapter you will be able to

  • Choose in-, il-, im- or ir- to make a word mean not
  • Use dis- and mis- to make opposites and wrong versions of words
  • Use de- to mean remove, reverse or undo
  • Use re- to mean again, and auto- to mean self
  • Use bi- to mean two, and work out a word from its parts
  • Check the meaning of a new word in a dictionary

You should already know

  • Adding prefixes such as un-, dis- and mis- (Year 4, Chapter 3)
  • Finding the root word and the suffix in a word (Chapter 1 of this book)

Where this leads

  • The Year 5-6 word list, silent letters and the dictionary and thesaurus (Chapter 3 of this book)

National Curriculum for England, Key Stage 2 English, Year 5. Content: Spell and use prefixes in-, il-, im- and ir- that mean not (SP-Y5e), Use dis- and mis- to make the opposite or a wrong version of a word (SP4), Use de- to mean remove, reverse or undo, and re- to mean again (SP-Y5e), Use auto- to mean self, and bi- to mean two (SP-Y5e), Work out a word's meaning from its prefix and root, then check in a dictionary (SP-Y5f).

Exercise P  Do you remember?

1
FWrite the root word in unhappy.
2
FAdd the prefix re- to the verb write. Write the new word.
3
FAdd the prefix mis- to the verb spell. Write the new word.
4
FAdd the prefix un- to the verb tie. Write the word that means to undo a tie.
5
FAdd the prefix im- to the adjective possible. Write the word.
2.1

Prefixes that mean not: in-, il-, im- and ir-

Year 5
Spell and use prefixes in-, il-, im- and ir- that mean not (SP-Y5e)
Video lesson: Prefixes that mean not: in-, il-, im- and ir-Coming soon
Story. Ravi is writing the rules for a club. One rule says that a member must not be inactive for a month. Another says that a payment that is incorrect or illegal must be reported. He notices that the prefix changes before different letters.

Key pattern

Several prefixes mean not. The prefix in- is used before most letters: active becomes inactive.

Before l, the prefix becomes il-: legal becomes illegal.

Before m, p or b, the prefix becomes im-: mature becomes immature; patient becomes impatient.

Before r, the prefix becomes ir-: regular becomes irregular.

Key ideas

  • in- means not, and it is used before most letters: incorrect, inactive.
  • il- is used before l: illegal, illogical.
  • im- is used before m, p and b: immature, impatient, imbalance.
  • ir- is used before r: irregular, irrelevant.
Worked example 2.1.1
Add a prefix to logical to make a word that means not logical.

Method. The root word starts with l, so the prefix is il-.

  1. Find the first letter of the root. Logical starts with the letter l.
    logical
  2. Choose the prefix. Before l, the prefix is il-.
    il + logical
  3. Write the answer.
    illogical

Check. Illogical means not logical. ✓

Worked example 2.1.2
Add a prefix to patient to make a word that means not patient.

Method. The root word starts with p, so the prefix is im-.

  1. Find the first letter of the root. Patient starts with the letter p.
    patient
  2. Choose the prefix. Before p, the prefix is im-.
    im + patient
  3. Write the answer.
    impatient

Check. Impatient means not patient. ✓

Worked example 2.1.3
Which word means not regular: irregular or inregular?

Method. The root word starts with r, so the prefix is ir-.

  1. Find the first letter of the root. Regular starts with r.
    regular
  2. Choose the prefix. Before r, the prefix is ir-.
    ir + regular
  3. Write the answer.
    irregular

Check. Irregular is correct. ✓

Exercise 2A  Practice: prefixes that mean not

1
FAdd a prefix to correct to make a word that means not correct.
2
FAdd a prefix to complete.
3
FAdd a prefix to active.
4
FAdd a prefix to legal.
5
FAdd a prefix to logical.
6
FAdd a prefix to patient.
7
FAdd a prefix to mature.
8
FAdd a prefix to balance.
9
FAdd a prefix to regular.
10
FAdd a prefix to relevant.
11
PSAli says inlegal is right. Write the correct spelling.
12
RExplain why impossible uses im- and illegal uses il-.
2.2

Prefixes dis- and mis-

Year 5
Use dis- and mis- to make the opposite or a wrong version of a word (SP4)
Video lesson: Prefixes dis- and mis-Coming soon
Story. Tara is making a poster about her favourite games. She writes that some people dislike losing, but that a good team does not mislead its players. Then she checks that she has used dis- and mis- correctly.

Key pattern

The prefix dis- often makes the opposite of a word: agree becomes disagree; honest becomes dishonest.

The prefix mis- means wrongly or badly: read becomes misread; spell becomes misspell.

Key ideas

  • dis- often means the opposite or the reverse of the root word.
  • mis- means wrongly or badly.
  • Check the meaning in a dictionary if you are not sure.
  • Do not confuse dis- with de-: dis- gives an opposite, and de- often means remove.
Worked example 2.2.1
Write the opposite of agree, using a prefix.

Method. dis- often makes the opposite of the root word.

  1. Find the root word. Agree is the root word.
    agree
  2. Add the prefix dis-. dis- means the opposite, so disagree means not agree.
    dis + agree
  3. Write the answer.
    disagree

Check. Disagree is the opposite of agree. ✓

Worked example 2.2.2
Write a word that means to read something wrongly, using a prefix.

Method. mis- means wrongly.

  1. Find the root word. The root word is read.
    read
  2. Add the prefix mis-. mis- means wrongly, so misread means read wrongly.
    mis + read
  3. Write the answer.
    misread

Check. Misread means read wrongly. ✓

Worked example 2.2.3
Which word means not honest: dishonest or misonest?

Method. The prefix for an opposite is dis-.

  1. Find the root word. Honest is the root word.
    honest
  2. Add the prefix. dis- makes the opposite, so dishonest means not honest.
    dis + honest
  3. Write the answer.
    dishonest

Check. Dishonest is correct. ✓

Exercise 2B  Practice: dis- and mis-

1
FAdd a prefix to agree.
2
FAdd a prefix to like.
3
FAdd a prefix to honest.
4
FAdd a prefix to appear.
5
FAdd a prefix to spell, to mean to spell wrongly.
6
FAdd a prefix to read, to mean to read wrongly.
7
FAdd a prefix to place, to mean to put in the wrong place.
8
FAdd a prefix to lead, to mean to lead someone the wrong way.
9
FWhich is spelt correctly: misunderstand or misundertand?
10
PSElla writes disapear in her story. Write the correct spelling.
11
PSA dictionary says mislead means to lead someone the wrong way. What does the prefix mis- mean?
12
RIs dismount the opposite of mount? Explain.
2.3

The prefix de-: remove, reverse or undo

Year 5
Use de- to mean remove, reverse or undo (SP-Y5e)
Video lesson: The prefix de-: remove, reverse or undoComing soon
Story. The school kitchen has a freezer full of ice. Before the trip, the cook must defrost the freezer, so that it works properly. She reads the label on the door, which says that the power must be deactivated first.

Key pattern

The prefix de- often means remove, reverse or undo: frost becomes defrost, which means to remove the frost.

de- can also mean to stop doing something: activate becomes deactivate.

de- does not always mean not. Use in-, un- or dis- for not, and use de- for removing or undoing.

Key ideas

  • de- often means remove, reverse or undo.
  • defrost means remove the frost or ice.
  • decode means undo a code.
  • deactivate means to stop something being active.
Worked example 2.3.1
Write the word that means to remove the frost from a freezer.

Method. de- means remove, so take the frost away.

  1. Find the prefix. The prefix de- means remove.
    de-
  2. Add the prefix to the root. Frost is removed, so the word is defrost.
    de + frost
  3. Write the answer.
    defrost

Check. Defrost means remove frost. ✓

Worked example 2.3.2
Write the word that means to undo a code.

Method. de- means undo, so take the code away.

  1. Find the prefix. The prefix de- means undo.
    de-
  2. Add the prefix to the root. Undo the code, so the word is decode.
    de + code
  3. Write the answer.
    decode

Check. Decode means undo a code. ✓

Worked example 2.3.3
Which means to remove someone from a throne: enthrone or dethrone?

Method. de- means remove, so dethrone means remove from a throne.

  1. Find the prefix. The prefix de- means remove.
    de-
  2. Choose the word. Enthrone means place on a throne, so dethrone is the opposite.
    dethrone
  3. Write the answer.
    dethrone

Check. Dethrone means remove from a throne. ✓

Exercise 2C  Practice: de-

1
FWrite the word that means to remove the frost from a freezer.
2
FWrite the word that means to undo a code.
3
FWrite the word that means to stop something being active.
4
FWrite the word that means to remove the water from food, such as to dry it out.
5
FWhich means to remove from a throne: enthrone or dethrone?
6
FWrite the verb that means to clear the trees from an area of land.
7
FWhich means to remove the ice from a fridge: defrost or disfrost?
8
FWrite the word that means to make something no longer active.
9
FWrite the word that means to reverse the coding of a message.
10
PSBen says that de- always means not. Is he right? Explain.
11
PSWrite the word that means to take the salt out of sea water.
12
RExplain what the word deactivate means, using its prefix.
2.4

The prefixes re- and auto-: again and self

Year 5
Use re- to mean again, and auto- to mean self (SP-Y5e)
Video lesson: The prefixes re- and auto-: again and selfComing soon
Story. Mia has been asked to rewrite her story after the teacher reads it. The school library has an autobiography of a famous scientist, which Mia reads to find out about the scientist's own life. She notices that re- and auto- are both useful prefixes.

Key pattern

The prefix re- means again: write becomes rewrite, which means to write again.

The prefix auto- means self: graph (writing) becomes autograph, which is your own signature.

Automatic means working by itself. An autobiography is a book about a person's life, written by that person.

Key ideas

  • re- means again: replay, reheat, rebuild.
  • auto- means self: automatic, autograph, autobiography.
  • The root word tells you the action or thing; the prefix tells you how or when.
  • Check a dictionary if you are not sure.
Worked example 2.4.1
Write the word that means to heat something again.

Method. re- means again.

  1. Find the prefix. re- means again.
    re-
  2. Add it to the root. Heat again is reheat.
    re + heat
  3. Write the answer.
    reheat

Check. Reheat means heat again. ✓

Worked example 2.4.2
Write the word that means working by itself.

Method. auto- means self, so the word means moving or working by itself.

  1. Find the prefix. The prefix auto- means self.
    auto-
  2. Add the root. The root word is matic, from the idea of moving by itself.
    self + moving
  3. Write the answer.
    automatic

Check. Automatic works by itself. ✓

Worked example 2.4.3
Which is a book about a person's own life, written by that person: autobiography or biography?

Method. auto- means self, so the book is written by the person about themselves.

  1. Find the prefix. Auto- means self.
    auto-
  2. Compare the words. A biography is written about someone; an autobiography is written by the person about their own life.
    autobiography
  3. Write the answer.
    autobiography

Check. Autobiography is correct. ✓

Exercise 2D  Practice: re- and auto-

1
FAdd re- to write.
2
FAdd re- to play, to mean play again.
3
FAdd re- to heat.
4
FAdd re- to build.
5
FWrite the word that means to start again.
6
FWrite the word that means working by itself, without a person.
7
FWrite the word that means a book about your own life, written by you.
8
FWrite the word that means your own handwritten name, such as on a card or book.
9
FWhich is spelt correctly: restart or restert?
10
PSWhich prefix means again: re- or auto-?
11
PSSam says that autograph means a book written by a robot. Is he right? Explain.
12
RExplain what reheat means, using its prefix.
2.5

The prefix bi- and working out a word's meaning

Year 5
Use bi- to mean two (SP-Y5e), Work out a word's meaning from its prefix and root, then check in a dictionary (SP-Y5f)
Video lesson: The prefix bi- and working out a word's meaningComing soon
Story. Noor is reading about a bicycle race. She meets some new words: bilingual, biplane and bisect. She works out what each might mean from its parts, then uses a dictionary to check.

Working out a word

Step 1: find the prefix at the start, such as bi-, which means two.

Step 2: find the root word, such as cycle, which means wheel or circle.

Step 3: put the meaning of the parts together.

Step 4: check your idea in a dictionary.

Key ideas

  • bi- means two: bicycle (two wheels), bilingual (two languages), biplane (two wings).
  • Work out the meaning from the prefix and the root word.
  • Check your idea in a dictionary, because some words have more than one meaning.
  • bisect means to divide into two equal parts.
Worked example 2.5.1
Work out the meaning of bicycle from its parts.

Method. bi- means two, and cycle means wheel or circle.

  1. Find the prefix. bi- means two.
    bi-
  2. Put the parts together. Two wheels make a bicycle.
    two + wheel
  3. Write the answer.
    a vehicle with two wheels

Check. A bicycle has two wheels. ✓

Worked example 2.5.2
Work out the meaning of bilingual from its parts.

Method. bi- means two, and lingual means language.

  1. Find the prefix. bi- means two.
    bi-
  2. Put the parts together. Two languages make a bilingual person.
    two + language
  3. Write the answer.
    able to use two languages

Check. Bilingual means two languages. ✓

Worked example 2.5.3
Which word means to divide into two equal parts: bisect or bicycle?

Method. Think about what the word means, using the prefix bi-.

  1. Find the prefix. bi- means two.
    bi-
  2. Check the meaning. Bisect means to cut into two equal parts.
    bisect
  3. Write the answer.
    bisect

Check. Bisect means to divide into two parts. ✓

Exercise 2E  Practice: bi- and working out meanings

1
FWhat does the prefix bi- mean?
2
FWrite the word that means to cut into two equal parts.
3
FWork out the meaning of biplane, using its parts.
4
FWork out the meaning of disconnect, using its parts.
5
FWork out the meaning of inaudible, using its parts. (Audible means able to be heard.)
6
FWork out the meaning of misjudge, using its parts.
7
FWork out the meaning of misinform, using its parts.
8
PSRuby says that misjudge means judge wrongly. Is she right? Explain.
9
PSExplain how a dictionary helps you check a word that you worked out from its parts.
10
RAli wants to find the word disagree in a dictionary. What should he look at first, and then next?

Chapter summary

SkillMethod
in-, il-, im-, ir- (not)in- before most letters; il- before l; im- before m, p or b; ir- before r.
dis- and mis-dis- gives the opposite (agree, disagree); mis- means wrongly (read, misread).
de-de- means remove, reverse or undo (frost, defrost; code, decode).
re- and auto-re- means again (write, rewrite); auto- means self (graph, autograph; biography, autobiography).
bi-bi- means two (cycle, bicycle; lingual, bilingual).
Working out meaningsFind the prefix and the root, put the meanings together, then check in a dictionary.

Can you…?

  • I can use in-, il-, im- and ir- to make a word mean not
  • I can use dis- for an opposite and mis- for wrongly
  • I can use de- to mean remove, reverse or undo
  • I can use re- for again and auto- for self
  • I can use bi- for two
  • I can work out a word from its prefix and root, then check in a dictionary

Key terms

prefix
letters added to the start of a word to change its meaning, such as un- in unhappy
root word
the word that a prefix or suffix is added to
opposite
a word with the reverse meaning, such as hot and cold
dictionary
a book that lists words in alphabetical order with their meanings
self
of or by oneself, as in an autobiography
equal parts
parts that are the same size, as in two halves

Exercise 2Z  Check-up

1
Add a prefix to correct to mean not correct.
2
Add a prefix to legal to mean not legal.
3
Add a prefix to patient to mean not patient.
4
Add a prefix to regular to mean not regular.
5
Add a prefix to like to mean the opposite of like.
6
Add a prefix to place to mean to put in the wrong place.
7
Write the word that means to remove the frost from a freezer.
8
Write the word that means to write again.
9
Write the word that means working by itself.
10
Work out the meaning of bicycle from its parts.

Total 18 marks. Allow about 18 minutes.

Exercise 2X  Practice test questions

1
FWrite the word that means not active, using the prefix in-.[1 mark]
2
FWrite the word that means to spell wrongly.[1 mark]
3
FWrite the word that means to undo a code.[1 mark]
4
FWrite the word that means not regular.[1 mark]
5
PSExplain what the prefix mis- means in the word misread.[2 marks]
6
PSWork out the meaning of disconnect, using its parts, and write it in your own words.[2 marks]
7
PSWrite the word that means a book about a person's own life, written by that person, and say which prefix means self.[2 marks]
8
PSWrite the word that means to divide into two equal parts, and say what the prefix bi- means.[2 marks]
9
PSAli says that disagree and misunderstand both use prefixes that mean wrongly. Is he right? Explain.[3 marks]
10
PSWrite the word that means not possible, and say which letter the prefix comes before.[3 marks]
← Chapter 1: Suffixes: -cious, -tial, -ant, -able and -ationChapter 3: The Year 5-6 word list, silent letters and the dictionary →

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