Giving a purpose: to and so that
Short answer: To explain why someone does something, use to plus the plain verb: He went home to eat lunch. You can also use so that plus a full idea with its own subject and verb: We wear helmets so that we stay safe. Use to, not for, before the verb, and use the plain verb after to.
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At a glance
| Pattern | Use | Example |
|---|---|---|
| action + to + plain verb | same person does both | I use a bag to carry my books. |
| action + so that + subject + verb | full idea, can use can or could | I came early so that I could sit near the door. |
| not: for + verb | wrong | not: for carry |
In short
- to + the plain action word: the purpose.
- so that + subject + verb: the purpose as a full idea.
- Use to, not for, before the action word.
What is the rule for “Why we do things: to and so that”?
The rule
to + the plain action word gives the purpose. so that + a full idea gives it too.
How it looks
action + to + plain action word · action + so that + subject + verb
What it means
They answer the question: Why?
When to use it
Use them to say why you do something.
How it works
- Ask: why does the person do it? The answer is the purpose.
- Short answer: to + plain verb.
- Longer answer with its own subject: so that + subject + verb (often can or could).
- Do not use for before a verb: I went to buy milk, not I went for buy milk.
Examples of “Why we do things: to and so that”
- He went home to eat lunch.
Why? To eat lunch. - I use a bag to carry my books.
Why? To carry my books. - We wear helmets so that we stay safe.
so that + we stay safe. - I came early so that I could sit near the door.
so that can have could. - She called me to ask a question.
Why did she call? To ask a question. - I save money to buy a bike.
Purpose: to buy a bike. - Speak slowly so that everyone can understand.
so that + subject + can. - He turned on the light so that he could read.
so that + subject + could.
Common mistakes with “Why we do things: to and so that”
I went to the shop for buy milk.→ I went to the shop to buy milk.
Use to, not for, before the action word.I went to the shop to bought milk.→ I went to the shop to buy milk.
After to use the plain action word.We wear helmets so that stay safe.→ We wear helmets so that we stay safe.
so that needs its own subject.I study hard for passing the exam.→ I study hard to pass the exam.
Use to + the plain verb for purpose, not for + -ing.I wear glasses so that I can to see.→ I wear glasses so that I can see.
After can, use the plain verb.
Exceptions: watch out
- so that and to
When the doer is the same, to is shorter: I wear a helmet to stay safe. so that is for a full idea.
To, for and so that
To and so that give a purpose with a verb. For is used with a noun: I went to the shop for milk.
| Pattern | Example |
|---|---|
| to + verb | I went to the shop to buy milk. |
| for + noun | I went to the shop for milk. |
| so that + idea | I went early so that I could buy milk. |
See also: Verb + -ing or to + verb
Check yourself
- Fill the gap: “I went to the shop ___ buy milk.”
Show the answer
to Purpose: to + plain verb.
- Fix: “I went for buy milk.”
Show the answer
I went to buy milk. Use to, not for, before a verb.
- Finish: “We wear helmets so that ___.”
Show the answer
we stay safe so that needs its own subject.
How to practice “Why we do things: to and so that”
The interactive version adds step-by-step help, spoken instructions and a quick check. One rule card, one sound lesson and the first lesson of every stone are free to try; the rest is part of Full Access. See Full Access.
- Practice lesson: Why we do things: to + verb and so that
Questions
When should I use “so that” and when “to”?
Use to when the same person does both actions. Use so that when there is a new subject or you want can or could.
Is “in order to” the same?
Yes. In order to is a longer, more formal way to say to.
Can I start with “To”?
Yes: To pass the exam, you must study. Put a comma after the to part.
More Linking Ideas Further rules
- before and after: before and after put two events in time order. Each part needs its own subject and verb.
- Past continuous: was / were + -ing: was or were + -ing tells what was happening at a time in the past.
- when and while in stories: while goes with the longer action (was / were + -ing). when goes with the short action that interrupts.
- Describing people with who: who adds information about a person. It takes the place of he or she, so do not say it twice.
- Describing things with that and which: that and which add information about a thing. Do not say the thing twice.
- although and even though: although and even though show that two ideas are different. Do not add but.
Used in these writing topics
Part of the 📘 Grammar tool. Level G5: Linking Ideas Further. Đọc bằng tiếng Việt.
Written for English learners by the English for Fun team. How we write our lessons · Last updated 2026-11-05.
Reviewed by Chinh Q. Hoang, PhD, founder, English for Fun · 2026-10-30