What you are controlling, in plain English
A clause is a group of words with a subject and a verb. A subordinate clause depends on a main clause to complete meaning. Relative clauses start with which, that, who and add information about a noun. Restrictive means essential to identify the noun. Non-restrictive means extra information only. Punctuation and linker choice decide clarity, tone, and score.

1) Because

Function: gives a reason.
Form: because + clause. For a noun, use because of + noun phrase.

Comma rule

• Middle or end: usually no comma.
• Beginning: comma after the because-clause.
• Avoid comma before because when it creates ambiguity.

Micro-contrast

• Because is explicit and strong. Since or as can mean time or cause; use because for exam clarity.

Mini patterns

• Precise: I delayed the project because the supplier missed two deliveries.
• With hedge: I delayed the project because, as far as I could tell, the supplier missed two deliveries.

2) Which vs That

Function: introduces a relative clause that describes a noun.

Restrictive (essential)

• Usually that in formal style. No commas.
• Example: The policy that reduces paperwork saved costs.

Non-restrictive (extra)

• which with commas.
• Example: The policy, which was trialled in Dhaka, saved costs.

Whole-clause reference

• Which can refer to the whole previous idea: The shipment arrived late, which caused inconvenience.

Safety rule

• Do not put a comma before that.
• In speaking, who is safer than that for people: the teacher who mentored me.

3) Although

Function: concession or contrast.
Form: although + clause. Do not combine with but in the same sentence.

Comma rule

• Start: comma after the although-clause.
• Middle: no comma before although unless for a long parenthetical.

Swap test

• Although X, Y ≈ While X, Y; However cannot replace although inside a clause.

Transformations

• Although prices rose, sales increased
  = Despite the rise in prices, sales increased.
  (Despite + noun phrase, not a clause.)

Two worked examples with annotations

Example A — Task 2 style
Original: People prefer online courses because they are flexible, which helps busy workers.
Improved: People prefer online courses because they are flexible, which helps busy workers who cannot attend fixed lectures.
[Because = reason; which = result referring to the whole idea; who = people, restrictive]

Example B — Report style
Original: The bridge that was built in 1998, improved traffic.
Improved: The bridge built in 1998 improved traffic.
Or, if essential identification is needed: The bridge that was built in 1998 improved traffic.
[No comma with restrictive that; reduced relative clause for concision]

Mini case — Nabila, Mirpur, Dhaka

Problem: Nabila overused commas with because and wrote double linkers like “Although X, but Y”.
Intervention: She ran a 14-day micro-drill: write 5 sentences daily using 1 because, 2 relative clauses (one which, one that), and 1 although. She checked three flags: comma placement, double linker, clause type.
Result: Errors dropped from 12 to 4 per 300 words, and her essays gained clearer logic. Her mock moved from 6.0 to 7.0.

Measurable drills

5-minute loop, three times a week

1. Write 4 sentences: because, which (non-restrictive), that (restrictive), although.
2. Read aloud and label each: reason, non-rest, rest, concession.
3. Reduce one relative clause per set: which → comma which; that → reduced clause where natural.
   Targets: ≤1 comma error per set; zero “although … but” cases; one whole-clause which per set.

Clause swap drill
Rewrite 3 sentences switching between:

• because ↔ because of
• although ↔ despite
• which non-restrictive ↔ that restrictive
  Score yourself for meaning preserved and punctuation correct.

Common mistakes

• Comma before because when the reason is essential.
• Comma before that.
• Double linker: Although…, but…
• Which used without commas in extra information.
• That used for people in formal writing where who is clearer.
• Using despite with a clause: use despite + noun, or although + clause.

Edge cases and fixes

• Ambiguity with because: I did not call him, because I was busy can imply the real reason is different. Prefer I did not call him because I was busy or I did not call him, as I was busy if you intend a soft aside.
• Stacked relatives: Choose one layer or split the sentence.
• Which vs that in British vs American style: Exams accept both if punctuation matches the choice; prioritise clarity.
• Reduced relatives: The report, which was published in May → The report, published in May. Use commas to keep it non-restrictive.

Tips and tricks

• Read the sentence aloud and pause at commas. If the meaning breaks, you likely used commas wrongly.
• Test necessity: if removing the clause changes identity, it is restrictive; use that or who without commas.
• In speaking, keep clauses short: stack one linker only.
• Convert long because-chains into one because and one result clause with which.

To avoid

• Writing although with however or but in the same sentence.
• Overcrowding one sentence with two or more subordinate clauses.
• Mixing because and because of.
• Using which to refer to people in formal writing.

Glossary

Restrictive clause: essential information that identifies the noun.
Non-restrictive clause: extra information set off by commas.
Relative pronoun: which, that, who, whose, whom introducing a relative clause.
Concession: admitting a limit before giving your main point.
Reduced relative: a shorter relative clause without who/which and be.

Next steps

Collect 10 sentences from your last essay. Label each clause type. Fix commas, swap one which for that when essential, and rewrite two sentences to remove a double linker. Aim to cut clause errors by 50 percent in two weeks.

1. Actionable closing — Checklist (do and avoid)

Do

• Use because + clause; because of + noun.
• Mark non-restrictive information with which and commas.
• Use that for essential information without commas.
• Start although-clauses with a comma after them; never add but in the same sentence.
• Try one reduced relative per paragraph for variety.
• Track errors per 300 words and target ≤5.

Avoid

• Comma before that.
• Double linker pairs: although…but, because…so.
• Which without commas when the information is extra.
• Despite + clause; fix to despite + noun or although + clause.

CTA: Edit one old paragraph now. Circle every because, which, that, and although. Apply the checklist, remove one double linker, and convert one clause to a reduced relative. Recount errors in 10 minutes and beat that number tomorrow.