Complete sentences and boundaries
Locate independent and dependent clauses before deciding where a sentence can end or how clauses may join.
What you will tackle
- Recognise finite independent clauses and dependent fragments
- Correct run-ons and comma splices
- Use sentence endings, semicolons and comma-plus-coordinator boundaries
A complete clause needs a finite verb
‘The archive preserves local maps’ is independent. ‘Because the archive preserves local maps’ is dependent: because creates an expectation of a main clause. A participial phrase such as ‘Preserving local maps’ does not by itself make a complete sentence.
Choose a grammatical relationship
Two independent clauses can be separate sentences, joined with a semicolon, or joined with a comma and a coordinating conjunction. A comma alone is a splice. Do not use a semicolon to separate a dependent clause from the main clause it completes.
Build your notes, then practise
Work on paper before opening an explanation. Guided tasks provide a starting point; independent tasks remove the scaffolding; application tasks ask you to justify a method or interpretation in context.
Guided practice
Guided 1
Repair ‘The storm ended, the researchers resumed work’ in three ways. Is ‘Because the storm ended’ a complete sentence?
Show a starting hint
Test each side as a sentence by itself.
Compare with the explained answer
- Both original clauses are independent, so a comma alone is insufficient.
- Use a period, a semicolon, or ‘, and’ between them.
- Because makes the final phrase dependent; it needs a main clause.
Answer / response criteria: ‘The storm ended. The researchers resumed work.’ ‘The storm ended; the researchers resumed work.’ ‘The storm ended, and the researchers resumed work.’ The because-clause is incomplete alone.
Independent practice
Independent 1
Choose the grammatical version and explain: A ‘The samples drying overnight.’ B ‘The samples dried overnight.’ C ‘Although the samples dried overnight.’
Compare with the explained answer
- A has a participle but no finite main verb.
- B has subject samples and finite verb dried.
- C is a dependent clause introduced by although.
Answer / response criteria: B is the complete independent sentence.
Application practice
Application 1
Revise ‘The route was short however it crossed a busy road’ to preserve the contrast without a run-on. Then add a dependent clause explaining why the group took extra care.
Compare with the explained answer
- However cannot join independent clauses by itself.
- Write ‘The route was short; however, it crossed a busy road.’
- A valid addition is ‘Because traffic was heavy, the group took extra care.’
Answer / response criteria: ‘The route was short; however, it crossed a busy road. Because traffic was heavy, the group took extra care.’
What can you explain now?
Revise ‘The route was short however it crossed a busy road’ to preserve the contrast without a run-on. Then add a dependent clause explaining why the group took extra care.
Compare with the explanation
‘The route was short; however, it crossed a busy road. Because traffic was heavy, the group took extra care.’
Explain the reasoning before comparing. This review records your self-assessment rather than an official score or mastery decision.
After trying it yourself, choose your next review. This is your self-assessment.
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Source and review status
Core coverage follows the detailed SAT skills in Appendix B of the September 2026 framework. The conditional School Day Essay is separate. The framework is maintained rather than issued as an annual subject syllabus.
Original teaching and explained self-check practice are available. Independent subject-specialist review and difficulty calibration remain pending; this is not an exam-board endorsement or a mastery certificate.
Official source specification / guide