Clauses of Purpose

In the English language, there are clauses that are used to express purpose. They are preceded by these words or expressions:

TO + Infinitive

* We use to + infinitive to express why an action is done.

We went to the gallery to support our friend on his photo exhibition.

IN ORDER THAT and SO THAT

IN ORDER THAT

* In order that is more formal and less commonly used than so that.

In order that you can join the organization, please fill out this form.

SO THAT

* We use so that to express that someone performs an action and someone else can consequently do or doesn’t have to do something else anymore.

I cooked some of his favorite dishes so that he can eat well again.

* We use so that + can / could / will be able to / would have to express that one action is possible because of the other one.

We left the office early so that we would have time to have dinner before going home.

* We use so that + don’t have to / won’t have to / wouldn’t have to to mean that one action will help avoid having to do something else.

I’m going to study hard so that I won’t have to worry so much before the exam.

* We use so that + won’t / wouldn’t / don’t to say that one action will prevent another thing to happen.

I always try to stay calm so that I don’t get into altercations.

IN ORDER TO / SO AS TO

* In order to is used the same way as to. However, to cannot be used before a negative infinitive. In this case, we use in order to.

Incorrect: To not be late for work, I woke up earlier this morning.
Correct: In order not to be late for work, I woke up earlier this morning.

Incorrect: They invested their money very strategically to not suffer a great loss.
Correct: They invested their money very strategically in order not to suffer a great loss.

* In order to or so as to is often used before stative verbs such as know, seem, appear, understand, have, etc.

They had a very long meeting about the issue so as to have a better understanding of the situation.

He tried to study his presentation all night in order to know every little detail of it.

FOR + noun

* We use for + noun to express purpose.

She is working hard for a chance at a promotion.

FOR + gerund

* We use for + gerund to express purpose and/or function of something.

Her efforts are all for raising awareness about climate change.