-s and -es endings
The endings -s and -es have three regular pronunciations determined by the final sound of the base, not by spelling alone.
01 · Concept foundation
Understand the terms before applying the rule
Each term below names a different grammatical object. Open examples and compare their function rather than memorising a Vietnamese translation alone.
voicing/ˈvɔɪsɪŋ/
độ rung thanhThe presence or absence of vocal-fold vibration during a speech sound.
voiceless /p, t, k/ versus voiced /b, d, ɡ/
vô thanh /p, t, k/ so với hữu thanh /b, d, ɡ/
sibilant/ˈsɪbɪlənt/
âm xuýtA high-friction sound such as /s, z, ʃ, ʒ, tʃ, dʒ/ that triggers an extra syllable /ɪz/.
washes /ˈwɒʃɪz/
washes /ˈwɒʃɪz/
allomorph/ˈæləmɔːf/
biến thể hình vịOne of several phonological realizations of the same grammatical morpheme.
/s/, /z/, /ɪz/
/s/, /z/, /ɪz/
Complete lesson scope
Do not stop at one formula
/s/, /z/ and /ɪz/ allomorphs
Final voicing and sibilant environments
Plural, possessive and third-person grammatical functions
Spelling changes and syllable preservation
Decision boundary: Pronunciation follows the final sound of the base, not the final written letter.
02 · Controlling rule
The spelling -s/-es can mark plural number, third-person singular present agreement, possession or a contraction. Its pronunciation follows the final sound, not the final letter: /s/ after a voiceless non-sibilant, /z/ after a vowel or voiced non-sibilant, and /ɪz/ after a sibilant. Meaning must therefore be identified before sound.
plural / 3SG / possessive / contraction → final sound → /s/ | /z/ | /ɪz/Inflectional -s/-es: grammar, spelling and sound
Distinguish plural, third-person agreement, possession and contracted auxiliary meanings, then select the correct spelling and /s/, /z/ or /ɪz/ realisation from the final sound.
Meaning chooses the morpheme; spelling records it; the final sound of the base chooses the pronunciation.
The same written ending is an allomorph system. It adds a syllable only after sibilants; elsewhere it attaches as one consonant, even when a consonant cluster is difficult.
What does -s mean here: plural, agreement, possession, is or has?
Does the base end in a sibilant, another voiceless sound, or a voiced sound?
Does the spelling require -s, -es, -ies or an irregular plural?
Can the listener still hear the grammatical contrast without an inserted vowel?
Four grammatical functions
Before pronunciation, identify what the ending contributes to sentence structure.
plural noun | 3rd-person verb | possessive | 's = is/hasPlural -s marks more than one countable item: sensor → sensors.
Third-person -s marks present-simple agreement with he, she, it or a singular noun phrase.
Possessive 's attaches to the possessor phrase, not automatically to the nearest noun.
Contracted 's means is before V-ing/adjective/noun, but has before a past participle.
The sensor records ten measurements per minute.
records /rɪˈkɔːdz/Cảm biến ghi mười phép đo mỗi phút.
Records carries third-person agreement because the singular head sensor controls the verb.
The researchers' notes were archived.
researchers' /rɪˈsɜːtʃəz/Ghi chép của các nhà nghiên cứu đã được lưu trữ.
The plural noun already ends in -s, so possession is shown by an apostrophe only; pronunciation does not add another syllable.
Plural noun
/s/, /z/, /ɪz/count noun + -s/-esMarks more than one countable referent.
three peaks
two gauges
several models
- Mass nouns do not become plural merely because the quantity is large.
Third-person agreement
/s/, /z/, /ɪz/he/she/it/singular NP + present verb-sMarks present-simple agreement with a singular third-person subject.
It works.
The tide rises.
The sensor measures pressure.
- After does, use the base verb: Does it work?
Possession
/s/, /z/, /ɪz/singular possessor + 's | plural possessor ending in s + 'Links a possessor or associated entity to a following noun.
the model's error
the students' reports
James's analysis
- Academic style often alternates between 's and of according to animacy, length and information flow.
Contracted is/has
/s/, /z/, /ɪz/ by the same sound rulesubject + 's + complement/V-ing/V3Shortens is or has in speech and informal writing.
She's ready.
She's working.
She's finished.
- The following form identifies the auxiliary: V-ing points to is; V3 commonly points to has.
Where the suffix goes
The station records waves.
Singular subject; the verb carries -s.
The stations record waves.
Plural subject; the noun carries -s and the verb is base form.
Do not copy -s onto both noun and verb; agreement distributes it according to the subject number.
Plural versus possession
three models
Three separate models.
the model's result
A result associated with one model.
An apostrophe is a grammatical marker, not decoration for every final s.
Letter versus sound
laughs /læfs/
The final sound is /f/, so the suffix is /s/.
moves /muːvz/
The final sound is voiced /v/, so the suffix is /z/.
Ignore silent letters and classify the last sound actually pronounced.
Both English and Vietnamese can express plurality, possession and time reference.
Vietnamese usually uses separate words or context, whereas English often places obligatory inflectional information on the noun or verb.
Vietnamese learners may omit final consonants, insert a vowel, or use one written -s rule without distinguishing grammatical function.
Say the base, identify the grammatical meaning, classify the final sound, then attach the shortest audible suffix.
When to use it in communication and IELTS
Everyday conversation
Prefer: Keep endings short but audible, especially when number or agreement carries new information.
Avoid: Adding a full vowel after every final consonant or deleting the suffix entirely.
English listeners use these small endings to recover grammar in fast speech.
IELTS Speaking
Prefer: Use accurate number and agreement consistently while maintaining natural rhythm.
Avoid: Over-articulating every suffix so strongly that speech becomes syllable-by-syllable.
Accuracy and intelligibility matter more than theatrical pronunciation.
IELTS/academic writing
Prefer: Check plural count nouns, third-person verbs and possessive apostrophes during editing.
Avoid: Using apostrophes to create ordinary plurals or omitting agreement in long noun phrases.
These are visible grammatical accuracy errors even when pronunciation is not assessed.
Build the correct suffix
Choose the grammatical function, then observe spelling, pronunciation and sentence position together.
Additional high-frequency grammar completed in GS8
Inflectional -s/-es
Plural number, third-person agreement, possession, spelling and the /s z ɪz/ sound system.
models · predicts · the model's output
Pronunciation table
Classify by sound, not spelling.
| Environment | Suffix | Examples |
|---|---|---|
| /p t k f θ/ | /s/ | maps, rates, peaks, cliffs, months |
| vowels and voiced sounds | /z/ | seas, models, trends, waves |
| /s z ʃ ʒ tʃ dʒ/ | /ɪz/ | classes, rises, washes, matches, gauges |
One sound, several grammatical functions
Syntax resolves meaning when pronunciation is identical.
| Function | Example | Diagnostic |
|---|---|---|
| plural | models | count noun; more than one |
| agreement | the model predicts | singular third-person subject |
| possession | the model's output | followed by a noun phrase |
| is/has | it's stable / it's changed | complement or participle identifies the auxiliary |
High-risk error bank
✕ The model predict higher peaks.
✓ The model predicts higher peaks.
A singular third-person subject requires present-simple agreement.
✕ The models predicts higher peaks.
✓ The models predict higher peaks.
A plural subject takes the base form of the present verb.
✕ Three sensor's failed.
✓ Three sensors failed.
Ordinary plurals do not take an apostrophe.
✕ maps /ˈmæpɪs/
✓ maps /mæps/
After /p/, the suffix is /s/ and does not create a new syllable.
Choose, submit and read the exact feedback
1. Which word takes /ɪz/?
2. Choose the correct agreement.
3. Which form is singular possessive?
4. Why is plays spelled with -s rather than -ies?
Transfer task
Record six paired sentences that move the suffix between noun, verb, possession and contraction, then annotate /s/, /z/ or /ɪz/.
- I identified the grammatical function before pronouncing the suffix.
- I classified the final sound rather than the final letter.
- I avoided unnecessary vowel insertion.
- My noun number and verb agreement are consistent.
03 · Worked examples
Observe form, function and meaning together
The model predicts higher peaks.
Mô hình dự báo các đỉnh cao hơn.
Three gauges record the water level.
Ba máy đo ghi lại mực nước.
The sensor's output is stable.
Đầu ra của cảm biến ổn định.
The process changes when salinity rises.
Quá trình thay đổi khi độ mặn tăng.
04 · High-risk contrast
Explain why one form fails, not only which answer is correct
The model predict higher peaks.
The model predicts higher peaks.
A singular third-person subject requires present-tense agreement, and predicts ends in /s/ because /t/ is voiceless.
05 · Mastery check
Apply the rule before marking the lesson complete
Which sentence is grammatically acceptable in the target system?
Which description best defines “voicing”?
Which example is one of the verified target patterns in this lesson?
Which structural formula belongs to this lesson?
Complete all four checks, then submit a sentence for target-form feedback.
06 · IELTS Academic
Transfer grammar into a real communicative task
Control of -s/-es supports subject–verb agreement, plural accuracy and intelligibility in Speaking. In Writing Task 1, graph descriptions frequently require singular verbs such as rises, shows and indicates; in Task 2, plural and possessive distinctions prevent ambiguity. In Speaking, the ending should be audible but not exaggerated into a separate syllable unless the base ends in a sibilant.
Explain the grammar–sound relation instead of memorising an isolated spelling rule.
Distinguish the target form from its nearest confusable alternative.
Produce one accurate spoken example and one formal written example.
Hear or infer the reduced form without deleting the required grammar in writing.