Cause and result are among the most frequent logical relationships in English — students use them to explain, justify, and report. The cause/result system in English is split between two grammatical families: conjunctions (because, since, as) introduce dependent cause clauses within a sentence, and connectors (so, therefore, consequently, as a result) link ideas across sentences or independent clauses. Students who mix these families produce consistent punctuation and structural errors. This lesson applies the conjunction/connector framework introduced in Lesson 4 (contrast words) to cause and result — a direct transfer that helps teachers and students see the same underlying pattern in a new context. Cross-reference: the difference between 'so' (result) and 'so that' (purpose) is covered in Lesson 7 of the adverbs series.
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.
All four sentences express the same cause-and-result relationship. What grammatical differences can you spot? Which sentences use one sentence? Which use two? What punctuation differences are there?
'Because' is a subordinating conjunction — it introduces a dependent cause clause within one sentence. It can come before or after the main clause. 'Therefore' is a connector — it begins a new sentence and takes a comma after it. 'So' as used here is a coordinating conjunction — it joins two independent clauses within one sentence with a comma before it. All three express result, but the grammar of each is different. This is the same conjunction/connector distinction introduced in Lesson 4 for contrast words — the pattern is identical, and recognising it helps students transfer the rule.
All three sentences express the same cause. Can you identify any differences in meaning or register between 'because', 'since', and 'as'?
All three are subordinating conjunctions expressing cause, but they differ in tone. 'Because' is the most direct and most common — it answers the question 'why?' explicitly. 'Since' is used when the cause is already known or can be assumed by both speaker and listener — it has a slightly more formal tone. 'As' is the most formal of the three and is common in written English. In everyday speech, 'because' is almost always the safest choice. Note also that 'since' has a separate time meaning ('since 2015') — see Lesson 3 of the adverbs series for the tense implications of time 'since'.
These two sentences look very similar. What is the difference in meaning? Is the result in the first sentence intentional or simply what happened? What about the second?
In the first sentence, 'so' is a coordinating conjunction expressing result — passing is what actually happened as a consequence. In the second, 'so that' is a subordinating conjunction expressing purpose — passing is a deliberate goal that the student had in mind while revising. The distinction is: 'so' = what happened (consequence); 'so that' = what was intended (purpose). This is covered in full in Lesson 7 of the adverbs series. Students frequently omit 'that' and write 'so' when they mean purpose — resulting in ambiguity or the wrong meaning.
| Tense / Form | Use / Meaning | Example | Key time words |
|---|---|---|---|
| Word | Type | What follows it | Punctuation rule |
| because | Conjunction (cause) | Subject + verb (dependent clause) | Comma after clause if clause comes first |
| since / as | Conjunction (cause, formal) | Subject + verb (dependent clause) | Same comma rule as 'because' |
| so | Coordinating conjunction (result) | Independent clause | Comma before 'so' when joining two full clauses |
| therefore / consequently | Connector (result) | Complete new sentence | Full stop or semicolon before; comma after |
| as a result / for this reason | Connector (result) | Complete new sentence | Full stop before; comma after the phrase |
The 'because...so' collision is one of the most widespread conjunction errors at B1 level and deserves direct, explicit teaching. Many students produce it because in their first language a single sentence can use a cause marker and a result marker simultaneously. In English, a single sentence chooses one perspective: either the cause view ('because X happened, Y') or the result view ('X happened, so Y'). The cause conjunction and the result connector are alternatives, not partners. A useful classroom explanation: imagine the sentence as a balance. 'Because' tips the balance towards the cause; 'so' tips it towards the result. Using both tips the balance in two directions at once and the sentence falls over. Students who understand why the error happens, rather than simply being told it is wrong, are more likely to avoid it in future writing.
Quick checks: • Do both 'because' and 'so' appear in the same sentence? → Cause/result collision — remove one • Does 'therefore' or 'consequently' follow only a comma? → Add a full stop or semicolon before it • Does 'because of' appear before a full clause? → Replace with 'because' (conjunction) or add a noun phrase after 'because of' • Does 'so' express a deliberate goal? → Replace with 'so that'
Choose the correct cause or result word for each sentence.
Each sentence has one cause or result error. Find and correct it.
Use this sequence directly in class — guided discovery, no textbook needed. Tap each step to mark it done.
STEP 1 — Transfer from Lesson 4 (5 min): Remind students of the conjunction/connector distinction from Lesson 4 (contrast words). Ask: can you think of any cause or result words that might follow the same pattern? Elicit suggestions. Then show how 'because' (conjunction) and 'therefore' (connector) are examples of the same two families applied to cause and result.
STEP 2 — The collision explained (7 min): Write a 'because...so' collision sentence on the board. Ask: what is wrong? After students respond, explain using the balance metaphor — a sentence can take a cause view (because) or a result view (so), but not both simultaneously. Ask students to correct the sentence in two ways: keeping 'because' only, then keeping 'so' only.
STEP 3 — So or so that? (5 min): Write pairs of sentences on the board — one with 'so' (result) and one with 'so that' (purpose). Ask students to identify which expresses what happened and which expresses what was intended. Introduce the rule: so = result; so that = purpose. Reference Lesson 7 of the adverbs series for those who want more depth.
STEP 4 — Because or because of? (8 min): Write six sentence starters on the board, each requiring either 'because' or 'because of'. Students decide which to use by looking at what follows: a full clause → 'because'; a noun phrase → 'because of'. Check answers as a class.
STEP 5 — Consolidate: explain three school events (5 min): Ask each student to explain three things that happened at school this week, each using a different cause or result word (because, so, therefore, consequently, as a result). Students must not repeat the same word. Pairs check each other's punctuation.
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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