Zero Conditional Lesson

Zero Conditional Lesson (Download)
Zero Conditional Matching Cards (Download)
Student worksheet (Download)

The zero conditional is used to express something that is scientifically proven or something that is generally true. It is also used to convey rules and communicate instructions.

In a zero conditional sentence the conditional clause can use a variety of present verb forms but the result clause must use the present simple or the imperative form of the verb. The result clause can also use modal verbs.


If/When/Unless clause (condition)                  Main clause (result)

If /When/Unless this thing happens                 that thing happens.

If you freeze water, it turns to ice.

Water turns to ice if you freeze it.

In a zero conditional sentence, the clauses are interchangeable but pay close attention to where the comma goes. Only use a comma if the conditional clause comes first.

If you freeze water, it turns to ice.

Water turns to ice if you freeze it.

When you heat ice, it melts.

Ice melts when you heat it.

Unless you water the flowers, they die.

 Flowers die unless you water them.

If you raise your hand, you can ask a question.

You can ask a question if you raise your hand.


Exercise 1: below are examples of different categories the zero conditional can be used for. Show students the categories one by one and have them, in groups, brainstorm more examples following the rules for the zero conditional.


Classroom rules:

  1. If you want to ask a question, you must raise your hand.

  2. You must apologise to the whole class if your phone rings.

(3 minutes to brainstorm more classroom rules)


Scientific facts and general truths:

  1. If you eat too much junk food, you gain weight.

  2. Water turns to ice if you freeze it.

(3 minutes to brainstorm more scientific facts and general truths)


Cause and effect:

  1. When you push this button, the curtains open.

  2. They pass the exams if they study long hours.

(3 minutes to brainstorm more cause and effect)



  1. When I work late, I drink lots of coffee.

  2. She wears her pink running shoes when she runs.

(3 minutes to brainstorm more routines)



  1. If he contacts you, tell me immediately.

  2. Finish the task alone if no one is free to help you.

(3 minutes to brainstorm more instructions)

Exercise 2: print out and cut up a set of cards for each group and instruct them to match two clauses to make zero conditional sentences.

As an extra activity, have each group work together to write the sentences accurately, focusing on the correct punctuation.

For higher level students or groups that finish quickly, have them write the other possible way each sentence could be written.


Exercise 3: correct the errors in the following zero conditional sentences.

  1. If students mess in class the teacher will punish them.

  2. When he went running, he wore his old shorts.

  3. Unless plants had enough sunlight and water they wither.

  4. Water will turn to ice unless you freeze it.

  5. If employees finish their work quickly, they will go home early?

Exercise 4 & 5: Student worksheet