Vocabulary Selection
The foundation of every LexFizz exercise is high-frequency, educationally relevant vocabulary. We do not select words arbitrarily or because they happen to appear in a single popular text. Our word selection process is grounded in established corpus-based frequency research.
Primary references for vocabulary selection:
- Oxford 3000 and Oxford 5000 (Oxford University Press) — the most widely used curated lists of high-frequency English words, covering the vocabulary most likely to be encountered in real-world reading, listening, and communication tasks. The Oxford 3000 forms the core vocabulary for A1–B2 exercises; the Oxford 5000 extends coverage for C1–C2 levels.
- New General Service List (NGSL) — a corpus-based frequency list derived from a 273-million-word corpus, providing objective frequency data to cross-check and validate vocabulary choices.
- Academic Word List (AWL) — used specifically when selecting vocabulary for academic English exercises and IELTS preparation content, covering the high-frequency academic vocabulary not included in general service lists.
A word is included in an exercise when it meets two criteria: it appears in at least one of the above reference lists at an appropriate frequency band, and it is educationally relevant — meaning a learner at the target CEFR level is likely to encounter it in authentic English use.
CEFR Level Assignment
Every exercise and article on LexFizz carries a CEFR level label (A1 through C2). These labels are not decorative — they are assigned through a deliberate process based on the Council of Europe's Common European Framework of Reference for Languages (2001, updated in the 2020 Companion Volume).
Level assignment takes into account:
- Vocabulary complexity: Cross-checked against the Oxford 3000/5000 frequency bands and NGSL frequency tiers to confirm the word is appropriate for the stated level.
- Grammar complexity: Evaluated against Cambridge Assessment English CEFR grammar scope-and-sequence documents and the CEFR can-do descriptors for each level.
- Background knowledge assumed: We consider whether the topic and context are accessible to a learner at the stated level without specialist knowledge.
- Exam alignment: Where relevant, level labels are cross-referenced with Cambridge Assessment exam syllabuses (A2 Key, B1 Preliminary, B2 First, C1 Advanced) to ensure learners have an accurate understanding of how the level corresponds to recognised qualifications.
Our CEFR level assignments are conservative. When a piece of content sits on the boundary between two levels, we label it at the higher level to avoid misleading learners about their readiness.
Exercise Design Principles
LexFizz exercises are designed according to principles from communicative language teaching (CLT) and second language acquisition (SLA) research. The goal of every exercise is not just to test what learners already know, but to create the conditions for new learning to occur.
Key principles applied in exercise design:
- Immediate feedback: Research consistently shows that corrective feedback delivered immediately after an error is more effective than delayed feedback. Every LexFizz exercise provides instant response to learner input.
- Spaced repetition built in: Exercises are structured to re-expose learners to target vocabulary across multiple rounds within a single session, mimicking the spacing effect documented in Ebbinghaus's forgetting curve research and popularised in SLA by Nation (2001).
- Meaningful context: Vocabulary and grammar items are presented in context wherever possible — in sentences, dialogues, or short texts — rather than in isolated word lists. This supports incidental learning alongside deliberate practice.
- Interactivity and engagement: Game mechanics (scoring, timers, visual feedback) are included not as gimmicks but because research in educational psychology (Mayer, 2009; Plass et al., 2015) demonstrates that motivational engagement increases time-on-task and improves retention.
- Accessibility: All exercises are keyboard navigable, ARIA-labelled, and tested against WCAG 2.1 AA contrast standards to ensure they are usable by learners with visual or motor impairments.
Content Quality Standards
Every page on LexFizz — whether an exercise landing page or a blog article — must meet minimum quality thresholds before publication:
- Minimum word count appropriate to the topic (exercise descriptions: 300+ words; blog articles: 1,500+ words).
- At least three unique, original example sentences per grammar rule or vocabulary item covered.
- No content that merely reproduces what is widely available elsewhere without a distinct educational angle or level-appropriate treatment.
- All factual claims about language (grammar rules, frequency data, exam requirements) verified against the primary sources listed in our Editorial Policy.
These standards are informed by Google's Helpful Content guidelines and our own commitment to producing resources we would confidently recommend to a student preparing for a Cambridge or IELTS exam.
Key Sources and References
| Source | Used For |
|---|---|
| Council of Europe CEFR (2001; 2020 Companion Volume) | Level descriptors, can-do statements, communicative competence benchmarks |
| Oxford 3000 / Oxford 5000 (OUP) | Core vocabulary selection and level-appropriateness |
| New General Service List (Browne, 2013) | Frequency-based vocabulary cross-checking |
| Academic Word List (Coxhead, 2000) | Academic and IELTS vocabulary selection |
| Cambridge Assessment English CEFR resources | Exam-level alignment and grammar scope-and-sequence |
| Cambridge Grammar of English (Carter & McCarthy, 2006) | Grammar rule verification |
| Swan's Practical English Usage (4th ed.) | Grammar clarification and usage notes |
| British National Corpus (BNC) / COCA | Naturalness and currency checks for example sentences |
Frequently Asked Questions
What word list does LexFizz use to select vocabulary?
LexFizz primarily uses the Oxford 3000 and Oxford 5000 (Oxford University Press) as its core vocabulary reference, cross-checked against the New General Service List (NGSL) for frequency data. The Oxford 3000 covers the most important words for A1–B2 learners; the Oxford 5000 extends this to C1–C2. The Academic Word List (AWL) is used for academic and IELTS-focused exercises.
How does LexFizz assign CEFR levels?
CEFR levels (A1–C2) are assigned based on three factors: vocabulary complexity (checked against Oxford 3000/5000 frequency bands), grammar complexity (evaluated against Cambridge Assessment CEFR scope-and-sequence documents), and background knowledge assumed. Level assignments are conservative — content on a level boundary is labelled at the higher level to avoid misleading learners. All assignments are cross-referenced with the Council of Europe CEFR (2001, 2020 Companion Volume).
Is spaced repetition used in LexFizz exercises?
Yes. Exercise structure is designed to re-expose learners to target vocabulary across multiple rounds within a single session, mimicking the spacing effect. This approach is grounded in Ebbinghaus's forgetting curve research and second language acquisition research by Nation (2001) on deliberate vocabulary learning. Flash Cards, Match Up, and quiz-style exercises are particularly designed with this principle in mind.
Why does LexFizz use a communicative teaching approach?
Communicative Language Teaching (CLT) is the dominant evidence-based approach in second language acquisition research. It emphasises using language in meaningful contexts rather than drilling isolated forms. LexFizz exercises present vocabulary and grammar within sentences, dialogues, and authentic contexts where possible, so learners encounter words as they are actually used — not just as definitions in a list.
Are LexFizz exercises aligned to any official exams?
Exercise content is aligned to CEFR levels and cross-referenced with Cambridge Assessment exam syllabuses (A2 Key, B1 Preliminary, B2 First, C1 Advanced) and IELTS requirements where relevant. This means learners preparing for these exams will encounter vocabulary and grammar structures appropriate to their target band. LexFizz is a supplementary practice resource — not an official exam preparation programme.
What is the New General Service List (NGSL) and why does LexFizz use it?
The New General Service List (NGSL), developed by Browne (2013), is a corpus-based frequency list derived from a 273-million-word corpus of contemporary English. It provides objective frequency data that is more current than older lists like the original General Service List (West, 1953). LexFizz uses the NGSL to cross-check that vocabulary selected via the Oxford lists is also genuinely high-frequency in modern English use.
How does LexFizz make exercises accessible to learners with disabilities?
All exercises are keyboard navigable with visible focus indicators, include ARIA labels for screen reader compatibility, and meet WCAG 2.1 Level AA colour contrast requirements. Animation-heavy exercises respect the prefers-reduced-motion media query to disable animations for users who need it. If you encounter an accessibility issue, please contact us via the contact page.
Does LexFizz use game mechanics, and is there research support for this?
Yes. Game mechanics such as scoring, timers, and visual feedback are included because educational psychology research (Mayer, 2009; Plass, Homer, and Kinzer, 2015) demonstrates that motivational engagement increases time-on-task and improves knowledge retention. The goal is not entertainment for its own sake but sustained practice — because more practice time directly correlates with better vocabulary and grammar acquisition.
What minimum content standards apply to LexFizz blog articles?
Blog articles must be at least 1,500 words, include a minimum of three unique original example sentences per grammar rule or vocabulary item, address a genuine learner question rather than keyword-stuffing, and have all factual claims verified against primary sources (CEFR, Oxford references, Cambridge Grammar of English). Articles that merely restate widely available information without a distinct educational angle are rejected at the planning stage.
Where can I read more about LexFizz's content standards?
For a full account of how content is researched, written, reviewed, and updated, see our Editorial Policy at lexfizz.com/editorial-policy/. For information about the team that creates content, see our Authors page at lexfizz.com/authors/lexfizz-team/. To contact us about methodology questions, use the contact page at lexfizz.com/contact/.