Sequences
Generating terms of a sequence and finding the nth term of a linear or quadratic sequence.
Full topic guide: the detailed syllabus page with worked examples and common mistakes lives at studyvector.co.uk/gcse/maths/algebra/sequences.
Topic preview: Sequences
Sample stems from the StudyVector question bank (AQA · Edexcel · OCR) — not generic filler text.
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Coverage and provenance
What this page is based on
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Topic explanation
A sequence is an ordered list of numbers that follows a rule. Arithmetic sequences have a constant difference between terms. Geometric sequences have a constant ratio. You need to find the next terms, describe the rule, and use the nth term formula. The nth term of an arithmetic sequence is a + (n-1)d, where a is the first term and d is the common difference.
Sequences is easiest to revise when it is treated as a precise exam behaviour, not a loose note-taking category. In GCSE Mathematics, the goal is to recognise how the topic appears in a question, identify the command word, and decide what evidence, method, or vocabulary earns marks. StudyVector keeps this page tied to AQA · Edexcel · OCR language where coverage is available, then routes practice towards the same topic so revision moves from explanation into retrieval.
A strong revision session starts with a short recall check. Write down the rule, definition, process, or method linked to Sequences before looking at any notes. Then answer one exam-style prompt and compare your answer with the mark-scheme logic: did you make a clear point, support it with the right step, and avoid drifting into a nearby topic? This matters because many lost marks come from almost-correct answers that do not match the expected structure.
Use this guide as the first layer: understand the topic, look at the worked examples, complete the mini quiz, then move into full practice. The full StudyVector practice loop is designed to capture whether mistakes are caused by knowledge, method, language, or timing. That distinction is important. If the error is factual, you need reteaching. If the error is method-based, you need a worked retry. If the error is wording, you need command-word calibration. That is how Sequences becomes a controlled revision target rather than another page in a folder.
Lost marks → repair task
Why marks are usually lost here
These are the error patterns StudyVector looks for after an attempt. The goal is not a generic explanation; it is one repair move and one follow-up question.
Unit, formula, or method slip
Examiner move: Select the correct method and keep units, substitutions, signs, and rounding visible.
Repair drill: Redo the calculation or method line slowly, naming the formula before substituting values.
Missing chain of reasoning
Examiner move: Show the link between point, method, evidence, and conclusion instead of jumping to the final line.
Repair drill: Write the missing because/therefore step, then retry one isomorphic question.
Timing breakdown
Examiner move: Match answer length to marks and avoid over-writing low-mark questions.
Repair drill: Set a one-mark-per-minute cap and write a compact version before expanding.
Mini quiz
Use these checks before full practice. They test topic recognition, exam technique, and whether you can connect the explanation to a marked response.
1. What should you check first when a Sequences question appears in GCSE Mathematics?
- A.The command word and the exact topic focus
- B.The longest paragraph in your notes
- C.A memorised answer from a different topic
2. Which revision action gives the strongest evidence that Sequences is improving?
- A.Rereading the explanation twice
- B.Answering a timed exam-style question and reviewing lost marks
- C.Highlighting every key phrase in the topic notes
Sample questions
Topic-specific public question previews are still being reviewed. We keep them off public pages until the topic match is safe.
Exam tips
- Read the command word carefully — "explain" needs reasons; "state" expects a short fact.
- For Sequences, show structured working even when you are practising multiple choice — it builds accuracy under time pressure.
- Mark yourself against the mark scheme style: one clear point per mark, in logical order.
- Come back to this topic after a day or two; short spaced reviews beat one long cram.
Worked examples
Example 1
Modelled exam response
Find the nth term of 5, 8, 11, 14, ... Common difference d = 3. Using the formula: nth term = 3n + 2. Check: 1st term = 3(1) + 2 = 5. ✓
Example 2
Identify the task before answering
Question type: a Sequences prompt asks for a clear response in GCSE Mathematics. Step 1: underline the command word. Step 2: name the exact part of Sequences being tested. Step 3: decide whether the mark scheme wants a definition, method, explanation, comparison, or calculation. Why it works: most weak answers fail before the content starts because they answer the topic generally rather than the exact exam task.
Example 3
Turn feedback into a repair task
Suppose your answer shows partial understanding but loses marks for precision. First, rewrite the missing mark as a short target: "I need to state the mechanism, unit, reason, or evidence explicitly." Then answer one similar question without notes. Finally, compare the second attempt with the first and check whether the same mark was recovered. Why it works: Sequences improves faster when feedback creates a specific retry, not another passive reading session.
Next revision routes from this subject
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Common mistakes
- Confusing the common difference with the first term when writing the nth term.
- Using n instead of (n-1) in the formula — the nth term is a + (n-1)d, not a + nd.
- Not checking whether a sequence is arithmetic, geometric, or neither before applying a formula.
- Forgetting that the nth term formula gives the general term, not the sum of terms.
FAQs
How do I find the nth term of a linear sequence?
Find the common difference d. The nth term is dn + (first term - d). For example, if the sequence is 5, 8, 11, ... then d = 3 and the nth term is 3n + 2.
What is a quadratic sequence?
A sequence where the second differences are constant. The nth term has the form an² + bn + c. Find a from the second difference, then work out b and c by substituting known terms.
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