The correct collocation is "Happy birthday," which is a common expression used to wish someone a pleasant and enjoyable birthday celebration.
Collocations
Collocation vs idiom: both are fixed expressions, but collocations are transparent (you can guess the meaning from the words: heavy rain = a lot of rain), while idioms are opaque (kick the bucket ≠ literally kick anything). Collocations are about which words pair naturally; idioms are about hidden meaning.
Collocations are habitual word combinations: make a decision, strong coffee, take a shower. Grammar allows alternatives, but fluency demands the conventional pairing.
Diagnostic: if the meaning is clear but the combination sounds "off" to native ears (do a mistake instead of make a mistake) — it's a collocation issue.
Vocabulary
Vocabulary vs grammar: grammar is the system of rules for combining words. Vocabulary is the stock of words themselves. You can have perfect grammar and still sound limited if your word stock is narrow (good instead of outstanding/remarkable/decent). Most fluency-feel above B1 comes from vocabulary breadth, not grammar complexity.
Vocabulary = word-focused learning: words, collocations, phrasal verbs, idioms, across CEFR A1–C2.
Diagnostic: can you express the idea but it sounds "flat" or overly simple? → vocabulary issue. Can't construct the sentence at all? → grammar issue.
Vocabulary for A1/Elementary/Beginner
A1 vs A2 vocabulary: A1 is survival — you can name things, ask basic questions, and follow short instructions. A2 adds social routine — small talk, plans, phrasal verbs. The jump from A1 to A2 is roughly doubling your word count from ~700 to ~1,500+.
A1 vocabulary = ~500–800 foundational words. Family, home, food, numbers, days, greetings, basic actions. The minimum for survival communication.
Diagnostic: can you introduce yourself, describe your family, and handle basic shopping/directions? Yes → A1 achieved. Struggling with routine social conversation beyond basics? → move to A2.
A1 | Elementary | Beginners
A1 vs A2: A1 covers isolated survival phrases (Where is…?, I am…, How much?). A2 handles connected sentences about familiar routines and simple past events. If you can manage short fixed phrases but not string together original sentences about your day, you're still A1.
A1 is the entry level of the CEFR: greetings, introductions, numbers, basic present tense, and core function words.
Diagnostic: can you describe yesterday using past tense? No → A1. Yes → you're moving into A2.
Easy
Easy vs Medium vs Hard: Easy = one rule, obvious answer, A1–A2. Medium = one rule but realistic distractors, A2–B1. Hard = interacting rules, edge cases, B2+. Start Easy to check you have the basics before moving up.
The Easy tag filters for single-rule, short-sentence, common-vocabulary challenges designed for beginners or for anyone wanting a confidence check on fundamentals.
Diagnostic: if you get Easy questions wrong, stay here — your foundations need work. If they feel trivial, move to Medium.