🔀 Lesson 2.1: Zero & First Conditional
Conditionals are how English talks about cause and result — "if this happens, that happens." In this lesson you'll master the two most useful ones: the zero conditional for facts that are always true, and the first conditional for real, likely futures. Get these right and you can talk about rules, plans, warnings, and predictions with confidence.
📚 What You'll Learn
By the end of this lesson, you will be able to:
- Form and use the zero conditional to state general truths and facts
- Form and use the first conditional to talk about real, likely future situations
- Punctuate conditionals correctly — a comma when the if-clause comes first
- Use when, unless, and future time words inside conditionals
⏱️ Estimated Time: 50–55 minutes
🎯 Project: Make six or more real predictions and plans about your own future using first conditionals — "If I …, I'll …" — and record or share them.
In This Lesson
What Is a Conditional?
A conditional sentence has two parts: a condition (the if-part) and a result. The condition sets up a situation, and the result tells you what happens because of it.
Every conditional is built from two clauses:
📖 The two clauses
The if-clause = the condition. If it rains…
The main clause = the result. …I'll stay home.
You can put them in either order: "If it rains, I'll stay home" or "I'll stay home if it rains." Same meaning.
English has several conditionals for different situations. This lesson covers the two that describe things that are true or genuinely likely — the zero and the first. (Next lesson we'll meet the second conditional, for imaginary situations.)
🧠 Mindset
Conditionals can feel like a maze of rules at first — but underneath, they follow one simple logic: match the verb to how real the situation is. Facts and likely futures use present + present or present + will. You don't need to memorize dozens of examples; you need to understand one pattern and trust it. Understanding beats memorizing every time. 🌱
The Zero Conditional
The zero conditional is for facts, general truths, and things that are always true. If the condition happens, the result always follows — like a law of nature or a rule.
📖 The form
If / When + present simple, present simple.
Both verbs are in the present simple. Notice there is no will anywhere.
| If / When-clause (condition) | Main clause (result) | Why it's zero |
|---|---|---|
| If you heat water to 212°F (100°C), | it boils. | always true — a fact |
| When I 'm tired, | I drink coffee. | my regular habit |
| If you don't water plants, | they die. | a general truth |
| If you press this button, | the machine starts. | how it always works |
✅ If ≈ When here
In the zero conditional, if and when mean almost the same thing, because the result is always true. "If I'm tired, I drink coffee" = "When I'm tired, I drink coffee." Both are fine. (This is not true for the first conditional — see below.)
The First Conditional
The first conditional is for real, possible future situations — things that might genuinely happen. You're not stating a permanent fact; you're talking about one specific likely future and its result.
📖 The form
If + present simple, … will / won't + base verb.
The if-clause stays in the present simple. The result uses will (or won't) + the base verb.
| If-clause (present simple) | Main clause (will / won't) |
|---|---|
| If it rains, | I 'll stay home. |
| If you study, | you 'll pass the exam. |
| If we leave now, | we won't be late. |
| If she calls, | I 'll tell her the news. |
Here's the whole pattern in one picture — the present-simple condition feeds a will-result:
graph LR
A["If + present simple"] --> B["result with will / won't"]
A --> C["condition: real, possible"]
B --> D["result: likely future"]
💡 The result clause can do more than will
Will is the default, but the result clause can also use can, may, might, or an imperative:
- If you finish early, you can go home. (permission)
- If it gets cold, we might stay in. (less certain)
- If you see John, tell him I said hi. (imperative / command)
The if-clause still stays in the present simple — only the result changes.
The One Rule You Must Not Break
This is the single most common conditional mistake at B1 — and once you fix it, your conditionals will sound right almost every time.
⚠️ Never put will after if
Use the present simple after if — not will.
❌ If it will rain, I'll stay home.
✅ If it rains, I'll stay home.
The will belongs in the other clause — the result. The if-clause always stays present, even though it's talking about the future.
Think of it this way: the future meaning is already inside the conditional. The word if plus a present-tense verb is enough to point at the future — so you don't need will there as well. Save will for the result, where it does its real job.
| ❌ Wrong | ✅ Correct |
|---|---|
| If you will call me, I'll help. | If you call me, I'll help. |
| If she will come, we'll start. | If she comes, we'll start. |
| If it will be sunny, we'll walk. | If it is sunny, we'll walk. |
Punctuation, When & Unless
The comma rule
Both clause orders are correct. The only difference is a comma:
💡 Comma when if comes first
If-clause first → use a comma: "If I see her, I'll tell her."
If-clause second → no comma: "I'll tell her if I see her."
Same meaning, same correctness — just remember the comma when you open with if.
When vs if in the future
In a future conditional, when and if are different — unlike in the zero conditional.
| Word | Meaning | Example |
|---|---|---|
| when | you're sure it will happen | When I get home, I'll call you. (I will get home) |
| if | it's possible, not certain | If I get the job, I'll celebrate. (maybe I will) |
Notice that when also takes the present simple for a future meaning — same rule as if. ❌ when I will get home → ✅ when I get home.
Unless = if not
⚠️ Unless means "if … not"
Unless is a shortcut for if … not. It introduces the one condition that would stop the result.
"I'll be late unless I leave now." = "I'll be late if I don't leave now."
After unless, use a positive present-simple verb (the "not" is already inside unless — don't add another one).
- You won't pass unless you study. (= if you don't study)
- Unless it stops raining, we'll stay in. (= if it doesn't stop)
📌 Zero vs First — the key contrast
Zero conditional = something always true. Result: present simple. "If you drop it, it breaks." (every time)
First conditional = one specific, likely future. Result: will. "If you drop it, it'll break." (this time, probably)
Ask yourself: a general rule, or one future moment? That tells you which one to use.
Hear it in a conversation
A: Do you want to go for a walk this afternoon?
B: Maybe. If it stays dry, I'll come with you.
A: And if it rains?
B: Then I'll stay home — unless you really want company!
A: Ha! Well, when I finish work, I'll text you. If the sky looks bad, we can just get coffee instead.
B: Perfect. If you text before three, I'll be ready.
🔊 Hear It & Repeat — Model Sentences
Listen to each model sentence, then say it back. Use the 🎧 Audio control (bottom-right) to choose a UK or US voice and slow the speed down. Notice the zero conditional for facts and the first conditional for likely future results.
- If you heat ice, it melts.
- Water boils if you heat it to a hundred degrees.
- If it rains tomorrow, we will stay at home.
- I will call you when I get to the station.
- If you don't hurry, you will miss the train.
Practice & Project
🏋️ Exercise 1: Put the verb in the right form
Objective: Present simple after if; will in the result. Some are zero, some are first.
- If you (heat) ice, it (melt). (fact)
- If it (rain) tomorrow, we (not go) to the beach.
- When I (get) home tonight, I (call) you.
- If you (study) hard, you (pass) the test.
- If you (press) this key, the screen (turn) off. (how it always works)
✅ Answer
1. heat … melts (zero — a fact) · 2. rains … won't go · 3. get … 'll call · 4. study … 'll pass · 5. press … turns (zero — always true)
🏋️ Exercise 2: Match the if-clause to the result
Objective: Join each condition (1–5) to its natural result.
- If you don't hurry,
- If it rains later,
- If you're hungry,
- If I pass the exam,
- If we tell her the news,
✅ Answer
1 → we'll miss the train · 2 → I'll lend you my umbrella · 3 → I'll make you a sandwich · 4 → my parents will celebrate · 5 → she'll be really happy
🏋️ Exercise 3: Rewrite as first conditionals / use unless
Objective: Turn each pair of ideas into one conditional sentence. For 4 and 5, rewrite using unless.
- Maybe I'll have time. Then I'll help you. → (If …)
- Perhaps you'll see Anna. Please give her this book. → (If … , imperative)
- Maybe we'll leave early. Then we won't hit traffic. → (If …)
- I'll be late if I don't leave now. → (… unless …)
- You won't succeed if you don't try. → (… unless …)
✅ Answer
1. If I have time, I'll help you. · 2. If you see Anna, give her this book. · 3. If we leave early, we won't hit traffic. · 4. I'll be late unless I leave now. · 5. You won't succeed unless you try.
🎯 Your Project: Six Predictions About Your Future
Speak out loud — to a partner, in class, or into your phone's recorder.
- (3 min) Brainstorm real situations that might happen soon: this weekend, next month, this year (weather, work, study, travel, family).
- (5 min) Turn each into a first conditional: "If I …, I'll …" — for example, "If I finish work early on Friday, I'll cook something nice."
- (3 min) Make sure you have at least six sentences. Include one with unless and one with when (something you're sure about).
- (2 min) Say them out loud, remembering: present simple after "if," "will" in the result.
- (2 min) If you recorded it, listen back: did you ever slip and say "if I will…"? Fix it and re-record one sentence.
✅ Project Completion Checklist
- ☐ I made six or more first-conditional sentences ("If I …, I'll …")
- ☐ I used the present simple after if (never "if I will")
- ☐ I put will / won't in the result clause
- ☐ I included one sentence with unless and one with when
- ☐ I used a comma when the if-clause came first
🎯 Quick Quiz
Question 1: Which sentence is correct?
Question 2: "I'll miss the bus ___ I run." Which word keeps the meaning "if I don't run"?
Tips & Common Mistakes
✅ Do's
- Ask "always true, or one likely future?" — that picks zero vs first for you.
- Keep the if-clause in the present simple, always — the future lives in the result.
- Add a comma when you start with if; drop it when if comes second.
- Use unless to say "if not" more smoothly — with a positive verb after it.
❌ Common Mistakes
⚠️ Watch Out
- Will after if: "If you will come" ❌ → "If you come" ✅.
- Double negative with unless: "unless you don't try" ❌ → "unless you try" ✅ (the "not" is already in unless).
- Missing comma: "If I see her I'll tell her" → add the comma: "If I see her, I'll tell her" ✅.
- Will in a zero conditional: "If you heat water, it will boil" is fine as a prediction, but for a plain fact say "it boils" ✅.
📓 Learning Journal
Keep your learning journal going. After this lesson, take a few minutes to write down:
- Key concepts you learned
- Things that clicked for you
- Questions or confusion points to revisit
- Ideas you want to try
- Your progress and feelings about reaching B1
✍️ This lesson's prompt: Write one zero conditional about a fact in your daily life ("When I drink coffee late, I can't sleep") and one first conditional plan for tomorrow ("If I wake up early, I'll go for a run"). Then explain in your own words why one uses the present simple in the result and the other uses will. Teaching yourself the reason is how the pattern becomes automatic.
📝 Lesson Summary
🎓 Key Takeaways
- Zero conditional = If/When + present simple, present simple — for facts and general truths always true.
- First conditional = If + present simple, … will/won't + base verb — for real, likely future situations.
- Never put will after if — the present simple carries the future; will goes in the result.
- Use a comma when the if-clause comes first; unless = "if … not" (with a positive verb).
🎉 What You've Accomplished
You can now talk about cause and result the way fluent speakers do — stating facts, making plans, giving warnings, and predicting likely futures. That single "if + present, will + result" pattern unlocks an enormous amount of everyday English, and you've locked in the rule that trips up most learners. 🎉
❓ Common Questions at This Stage
Can I use "will" in a zero conditional, like "If you heat water, it will boil"?
Yes, but it changes the flavor slightly. With boils (present) it's a pure scientific fact. With will boil it feels more like a prediction about a specific moment — that's really the first conditional. For plain, timeless truths, keep both verbs present.
What's the real difference between "if" and "when" in a future sentence?
Certainty. When = you're sure it will happen ("When I get home, I'll eat" — I will get home). If = it's only possible ("If I get the job, I'll celebrate" — maybe I will). Both still take the present simple, never will, in that first clause.
Does "unless" always mean exactly "if not"?
Almost always, yes, and for B1 you can treat them as equal. Just remember to use a positive verb after unless: "unless you hurry" (✅), not "unless you don't hurry" (❌), because the negative meaning is already built into the word.
🔭 Looking Ahead
Now that you can talk about real futures, the next step is imaginary ones. In Lesson 2.2: Second Conditional, you'll learn "If I had… I would…" — how to talk about situations that are unlikely, hypothetical, or simply not true, so you can dream, advise, and speculate.
✅ Before the Next Lesson
- Say five first-conditional plans out loud, each starting "If I…".
- Rewrite three of them using unless or when.
- Write your Learning Journal entry for this lesson.
🌟 Encouragement for the Journey
Conditionals are the language of possibility — plans, promises, warnings, and hopes all live here. Every time you say "If I…, I'll…," you're not just being correct; you're imagining a future and shaping it in words. That's a powerful, human thing to do in a second language. Onward to Lesson 2.2! 👋