If you asked even the most knowledgeable Americans, they probably could not tell you more than a few meanings for the word "so." It is an everyday word that most people use without even realizing its complexity.

But this mysterious little word can act as an adverb, pronoun or conjunction, with many meanings as each. In all, there are more than 25 meanings for "so." That's one powerful word!

Today, we will tell you about three phrases that English learners have trouble with: "so" "so that" and "so adjective/adverb that." We'll discuss each one then compare them.

Therefore...

Let's start with "so" as a coordinating conjunction – a word that joins two or more things, such as sentences or other words. When used in this way, it means "therefore" or "for that reason."

For this meaning, "so" joins two complete sentences and shows the result of something in the second sentence. Take a listen:

The apartment was too hot, so we opened the window.

The first sentence provides the action or situation: The apartment was too hot. It is joined by "so" to the second sentence which explains the resulting action: opening the window.

In order to...

OK, now we move to "so that," a phrase that begins adverb clauses. You may recall that an adverb clause shows a relationship between two actions. It joins a main clause, or complete sentence, to a dependent clause, or incomplete sentence, and shows how they relate.

"So that" means "in order to" which answers the question "Why?" We use it to begin adverb clauses of purpose. Let's hear an example:

It helps to lower blood sugar so that you feel less hungry.

The adverb clause is "so that you feel less hungry." It shows the purpose for the action in the main clause. Why does it help to lower blood sugar? To feel less hungry.

"So that" can also come at the beginning of a sentence but this is rarer and usually sounds stilted to Americans. Listen:

So that you feel less hungry, it helps to lower blood sugar.

One important note is that the word "that" is optional for "so that" in spoken English, so it may disappear. Here's how that sounds:

It helps to lower blood sugar so you feel less hungry.

But without "that," how will you know that the meaning is "in order to"? One signal is that there is often a modal verb in the adverb clause. Modal verbs include can, could, may, might, will and others. Here's how that might sound:

It helps to lower blood sugar so you can feel less hungry.

The modal verb in the adverb clause is "can."

A Metro advertisement in Washington, DC, uses one of the phrases from today's program. Do you know which it is? Can you understand the meaning?

To the level described...

Finally, let's discuss the phrasing "so adjective/adverb that." This is different from both meanings we've talked about. To try to put it simply, it means "to the level described." Here are some examples:

This morning, the construction was so loud that we could not sleep.

This means that the construction was loud to a level that prevented us from sleeping.

In the phrase "so adjective/adverb that," the word "that" begins a type of clause called a "complement clause," but we will not talk about that in today's program.

What's important today is knowing that the word "that" for this phrase is also optional and may disappear. Here's how it sounds:

This morning, the construction was so loud we could not sleep.

So, how might you know the meaning if "that" disappears? Well, you can listen for an adjective after "so." The adjective in our example is "loud."

Comparing the three

Now, we'll compare the three phrases. You will hear three sentences that sound similar but have different meanings:

He is funny, so his friends laugh at him.

The meaning here is: He is funny. Therefore, his friends laugh at him. Here's the next one:

He makes jokes so that his friends will laugh.

This means: He makes jokes for the purpose of making his friends laugh. It answers the question, "Why does he make jokes?" Notice the modal "will" in the adverb clause.

Now for the last meaning:

He is so funny that his friends laugh at him.

It means: He is funny to such a level that it makes his friends laugh at him.

Now for one more set to help you examine the meanings:

She studied hard, so she was able to win a scholarship.

The meaning here is: She studied hard. Therefore, she was able to win a scholarship. And the next one:

She studied hard so that she could win a scholarship.

It means: She studied hard for the purpose of winning a scholarship. Again, you see a modal in the adverb clause: could. And lastly:

She studied so hard that she won a scholarship.

This means: She studied hard to such a degree that she won a scholarship.

You probably noticed that some examples other than those with "so that" have modal verbs. All three of today's phrases can have modals, but "so that" adverb clauses commonly have them.

Well, we're so happy that you stayed around for today's program. Don't forget to do the practice, so that you can remember what you learned!

Alice Bryant wrote this story for Learning English. Caty Weaver was the editor.

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Words in This Story

phrase – n. a word or group of words that express an idea but do not usually form a complete sentence

clause – n. a part of a sentence that has its own subject and verb

stilted – adj. awkward especially because of being too formal

optional – adj. available as a choice but not required

modal verb – n. a verb that is usually used with another verb to express ideas such as possibility, necessity and permission

scholarship – n. n amount of money that is given by a school or organization to a student to help pay for the student's education

practice – v. to do something again and again in order to become better at it

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Now, you try it!

Rewrite each example with a "so" phrase from today's program. If an example is two separate sentences, make it into one sentence.

Example:I woke up early. For that reason, I went to the market. (so)I woke up early, so I went to the market.

We were having a great time. Therefore, we invited them to our house for dinner. (so)

Meet me at the theater by 7pm to get good seats. (so that)

His eyes were very tired. He could not read the words on the page. (so adjective that)

We took a taxi to the party to avoid waiting outside in the cold. (so that)

The dog ate the food very quickly. There was no food left for the other dogs. (so adverb that)

She stayed in the U.S. for three months for the purpose of studying English. (so that)

My phone broke. Therefore, I bought a new phone. (so)

I didn't want to go. For that reason, I didn't stay long. (so)

I wrote this program in order to show the difference between phrases. (so that)