Correlative conjunctions work in pairs — both parts must appear in the sentence, and the grammatical structures they connect must match. The four main pairs in English are both…and, either…or, neither…nor, and not only…but also. These conjunctions allow speakers and writers to connect two ideas in a balanced, elegant way. However, they generate two persistent errors: breaking the parallel structure (connecting a noun to a verb, or an adjective to a clause) and getting subject-verb agreement wrong when the subjects connected are different in number. This lesson gives teachers the knowledge to explain both clearly.
Before you start — think honestly about your own teaching and experience.
Look at the examples. Answer each question before reading the explanation — this is how your students will learn too.
The first sentence is natural; the second is repetitive and awkward. What does 'both...and' allow the first sentence to do that the second cannot? What is the same grammatical type on each side of the pair?
'Both...and' connects two noun phrases of the same grammatical type. This is called parallel structure — the elements on either side of a correlative conjunction must be the same type: noun with noun, verb with verb, adjective with adjective, clause with clause. Breaking the parallel structure produces awkward or ungrammatical sentences and is the most common correlative conjunction error.
Look at the three sentences. What does each pair signal? Notice the word order in the third sentence — why is 'did' placed before 'she'?
'Either...or' presents two alternatives. 'Neither...nor' negates both elements simultaneously, replacing 'not...and not'. 'Not only...but also' adds emphasis — the second fact is a surprising addition to the first. When 'not only' begins a sentence, subject-auxiliary inversion is required ('Not only did she mark...' not 'Not only she marked...'). This inversion mirrors the structure seen with 'nor' in coordinating conjunctions (Lesson 1 of this series).
All three sentences use 'either...or'. Why do the verbs differ? What rule determines which verb form to use when the two subjects are different?
When 'either...or' or 'neither...nor' connects two subjects, the verb agrees with the subject closer to it — this is the proximity rule. 'Either the head teacher or the deputy is...' — 'deputy' is singular and closest to the verb, so 'is'. 'Either the head teacher or the teachers are...' — 'teachers' is plural and closest to the verb, so 'are'. In formal and written English, proximity agreement is expected.
| Tense / Form | Use / Meaning | Example | Key time words |
|---|---|---|---|
| Pair | Meaning | Example | Watch out for |
| both…and | Includes both equally | Both the teacher and the students were tired. | Parallel structure: noun + noun |
| either…or | One or the other (choice) | Either finish now or stay after school. | Verb agrees with nearer subject |
| neither…nor | Negates both items | Neither the water nor the electricity worked. | 'Neither...or' is always wrong |
| not only…but also | Emphasises surprising addition | Not only did she teach well, but she also stayed late. | Inversion needed when 'not only' starts the sentence |
The parallel structure rule is deceptively easy to break because students focus on meaning rather than grammatical category. A useful classroom test: cover the first element of the pair and read only the second — does it complete the sentence correctly on its own? Then cover the second and read only the first. If both work independently in the same grammatical way, the structure is parallel. For example: 'Both the teacher explained clearly and using examples.' Cover the second: 'Both the teacher explained clearly' — odd. Cover the first: 'Both using examples' — also odd. The mismatch is revealed. Corrected: 'The teacher both explained clearly and used examples' (two past verb phrases — parallel). This self-checking technique requires no specialist knowledge and is useful for students to apply independently. Also worth noting: 'not only' + inversion is the same pattern as 'nor' + inversion in coordinating conjunctions (covered in Lesson 1 of this series) — students who have seen that pattern will find this one easier to grasp.
Quick checks: • Are both elements in the pair the same grammatical type? → Parallel structure ✓ • Does the sentence use 'neither...or'? → Change 'or' to 'nor' • Are there two different subjects connected by 'either...or' or 'neither...nor'? → Verb agrees with the nearer subject • Does 'not only' open the sentence? → Check for subject-auxiliary inversion after it
Complete each sentence using the correct correlative conjunction pair.
Each sentence has one error with a correlative conjunction. Find and correct it.
Use this sequence directly in class — guided discovery, no textbook needed. Tap each step to mark it done.
STEP 1 — Introduce the pairs (5 min): Write the four pairs on the board. Ask students to say what each one means before you explain. Give one example of each using classroom situations. Ask students to notice what the two items connected by each pair have in common grammatically.
STEP 2 — Parallel structure test (7 min): Write four sentences — two with correct parallel structure and two with broken parallel structure. Students in pairs identify which are correct and why. Introduce the cover test: cover each element and read only the other — if both work independently in the same grammatical way, the structure is parallel.
STEP 3 — Neither...nor: never 'neither...or' (5 min): Write 'neither...or' on the board with a large cross through it. Tell students: 'neither' always pairs with 'nor'. Ask students to give three sentences using 'neither...nor' about their school. Write the best examples on the board and check the agreement rule simultaneously.
STEP 4 — Agreement: who is closer? (8 min): Write five sentences with 'either...or' or 'neither...nor' connecting subjects of different number. Students decide which verb form is needed by finding the nearer subject. Reinforce: look right — the verb agrees with the nearest subject.
STEP 5 — Consolidate: three sentences (5 min): Each student writes three sentences — one using each of three different pairs — including one with subjects of different number and one with the parallel structure rule applied correctly. Students swap with a partner to check.
Use directly in class — copy, adapt, or read aloud. No printing needed.
For each strategy, choose the option that best describes where you are now.
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