Third Conditional

IF clause main clause
If I had studied harder,           I would have passed the exam.

Explanation: I failed the exam, because I didn’t study hard enough.

If the “if” clause comes first, a comma is usually used. If the “if” clause comes second, there is no need for a comma:

main clause IF clause
I probably would have passed the exam         if I had studied harder.

We use different verb forms in each part of a third conditional:

IF clause if + subject + past perfect verb*
  main clause subject + would (OR could, OR might) have + past participle

*The past perfect is formed with the auxiliary verb “had”, and the past participle (or third form) of the verb.

Using the third conditional

The third conditional is used to talk about things which did not happen in the past.  It is often used to express criticism or regret:

Example Explanation
If you had driven more carefully, you would not have had an accident. Criticism: You had an accident because you didn’t drive carefully enough.
If we had played a little better, we could have won the game. Regret: We didn’t play well, so we lost the game.
If you had saved your money, you could have bought a computer. Criticism: You didn’t save your money, so now you can’t afford a computer.
If it had snowed, we could have gone skiing. Regret: It didn’t snow, so we couldn’t go skiing.

Idea for using third conditional in class.  Language  focus: Speaking/Writing

What would have happened if?  Students have to think of different scenarios that encourage them to consider how actions in the past shape what happens in the future.  You can talk about global issues, national issues or focus on something that has happened in the student’s life.  What would have happened if the wheel hadn’t been invented?  What would have happened if we hadn’t discovered oil? What would have happened in your life if you hadn’t go married? etc.