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Commonly Confused Words: Their, There, Affect and Effect

Choose between their, there and they're, affect and effect, your and you're, and other mixed-up words, with a quick test for each pair.

  • ⏱ 3 min read
  • ✏️ 3 worked examples
  • 🎯 5 practice questions
  • 📶 Beginner
KS3GCSEMiddle SchoolHigh School
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Curriculum fit: GCSE English Language (spelling, punctuation and grammar). US: Common Core ELA Language standards (grades 6-10).

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What Is It?

Some words sound alike or look alike but have different meanings, so spellcheck often misses mistakes. Learning the most common pairs avoids marks lost for simple errors.

The trick is to learn a short test for each pair, such as replacing a word with its longer form.

their / there / they'rebelonging · a place · they areyour / you'rebelonging · you areaffect / effectverb: to influence · noun: a resultthen / thantime or order · comparisonto / too / twodirection · also · the number 2
Check which meaning you need before you choose. Reading the sentence aloud with the full words, such as they are, helps.

Key Formulas and Ideas

  • their (belonging to them), there (a place or 'there is'), they're (they are).
  • your (belonging to you), you're (you are).
  • affect (verb: to influence), effect (noun: a result).
  • then (time or sequence), than (comparison).
  • to (direction), too (also or excessive), two (the number).

Worked Examples

Example 1

Their, There, They're

Question

Fill in: '___ going to leave ___ bags over ___.'

  1. 'They are going' fits the first gap, so 'they're'.
  2. The bags belong to them, so 'their'.
  3. 'Over there' is a place, so 'there'.

✓ Answer They're going to leave their bags over there.

Example 2

Affect or Effect

Question

Choose: 'The weather will (affect / effect) the match.'

  1. A verb is needed, because it describes an action.
  2. 'Affect' is the verb.

✓ Answer affect

Example 3

Then or Than

Question

Choose: 'She is taller (then / than) her sister.'

  1. This is a comparison.
  2. 'Than' is used for comparisons.

✓ Answer than

Common Mistakes to Avoid

  • Writing 'your welcome' instead of 'you're welcome'.
  • Using 'effect' as a verb in everyday writing, instead of 'affect'.
  • Writing 'could of' instead of 'could have'.
  • Confusing practise (verb) and practice (noun) in UK English.

Practice Questions

0 of 5 answered
Q1Choose: '___ going to the park.'
Q2Choose: 'I have more books ___ you.'
Q3Choose: 'Late nights ___ my concentration.'
Q4Choose: '___ welcome to join us.'
Q5Which sentence uses the correct form?

Frequently Asked Questions

How do I remember affect and effect?

A is for action (affect is a verb) and E is for end result (effect is a noun).

Is 'practice/practise' different in US English?

In US English, 'practice' is used for both the noun and the verb.

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Sources and Review

Reviewed by StudyMorrow editorial review on 5 Nov 2026.