Comma Sense Lesson 1

COMMA SENSE CLASS

LESSON #1
COMMANDING THE COMMA

The comma appears to be a harmless little fellow, but don't let appearances deceive you. Sure, the little guy never shouts, never declares, never questions, never even finishes a sentence, for that matter, but that doesn't mean he holds no power. In fact, he is the hardest working of all the punctuation marks, the only one often appearing more than once in a single sentence. He holds the power to change the meaning of a sentence and to disrupt the flow of prose. Therefore, isn't it time to give the little guy his due and quit misunderstanding him?

Quoted from:
http://users.wirefire.com/tritt/tip18.html



    Please do not run in terror when you see the length and detail of Lesson #1. Particular basic grammar information needs to be explained here in order for you to understand how to properly place (or omit) a comma. The length is due to the numerous examples I have provided for each Comma Placement Rule. This is the most difficult lesson in the whole course. Lesson #1 lays the ground work for all subsequent lessons. If you can make it through these first seven rules of comma usage, you will find the rest of the course much easier to grasp. The remaining five lessons are much shorter. So calm down, relax, take a deep breath, and let's get started.

FIRST 7 RULES OF COMMA USAGE

[Scroll down to bottom of this page for list of Rules and Exceptions]

Rule #1: Independent Clauses Joined by Coordinating Conjunctions
Use commas to separate independent clauses when they are joined by Coordinating Conjunctions.

Independent Clauses can stand alone as a separate and complete sentence. When a Coordinating Conjunction joins these independent clauses, a comma is used. It may help you remember the seven Coordinating Conjunctions by recalling that they all have fewer than four letters and that the first letter of each spells out the acronym FANBOYS.
For-And-Nor-But-Or-Yet-So. These are the seven Coordinating Conjunctions.
The comma should always be placed before the coordinating conjunction.
Only when a Non-Essential Phrase immediately follows the coordinating conjunction do you need to use a comma after the conjunction.

Examples of Independent Clauses Joined by Coordinating Conjunctions:

New Horizons Academy offers courses in writing techniques, and it hires only the best instructors.
In this sentence, we have two independent clauses joined by a coordinating conjunction. New Horizons Academy offers courses in writing techniques can stand alone as a separate sentence. It hires only the best instructors is also an independent clause because it, too, can stand alone as a separate sentence. These clauses are joined by a Coordinating Conjunction, so a comma is needed before and.

I hate to waste a single crumb of Mom's salmon patties, for they are expensive and time-consuming to make.
See that coordinating conjunction and underlined in this sentence? Well, no comma goes before it because what follows (time-consuming to make) is not an independent clause. This is called a phrase, and no comma should precede and.

The chili is delicious, and it is hot.

McGregor refuses to eat dry cat food, nor will he touch the discount canned food.
When the coordinating conjunction nor is used to join two independent clauses, the second independent clause will always have inverted word order, and the verb will come before the subject, but it is still considered an independent clause.

McGregor loves having his head scratched, but I wouldn't touch his tail if I were you.

The chili is so thick you can eat it with a fork, or you can use a soup spoon.

McGregor terrorizes the poodle next door, yet he adores the old German shepherd across the street.

McGregor is finicky, so I have to add catnip to his lobster bisque.

We hoped that decorating the top of Cindy's cupcake with a dead grasshopper would freak her out, but, to our surprise, she just popped the whole thing in her mouth.
In this sentence, to our surprise is called a Non-Essential Phrase and should be surrounded by commas. That's why there is a comma before and after the coordinating conjunction but. You will learn more about Non-Essential Elements (Rule #5) further below in this Lesson.


Exception #1xa: Independent Clauses Joined by So That
There is an exception with the coordinating conjunction so:
You always put a comma before so when it joins two independent clauses UNLESS so is used in place of in order that. If the word that follows so, or the word that is implied after so, no comma should precede so. When used together as a combined conjunction inferring in order that, so that becomes a Subordinating Conjunction, and no comma is used.
Let me repeat:
SO THAT IS A SUBORDINATING CONJUNCTION (not a Coordinating Conjunction), AND NO COMMA IS USED!

Examples of Independent Clauses Joined by So That:

I have worked hard on the Comma Sense Lesson Pages so that my students may have every available source of information at their fingertips.
In this sentence, NO comma goes before the Coordinating Conjunction so because the word that follows it which makes the combination of so that a Subordinating Conjunction. Don't panic! We are about to learn about Subordinating Conjunctions.

I have worked hard on the Comma Sense Lesson Pages so my students may have every available source of information at their fingertips.
In this sentence, NO comma goes before the Coordinating Conjunction so because the word that is implied which makes so [that] a Subordinating Conjunction.

I have worked hard on the Comma Sense Lesson Pages, so that is why this is the most complete and comprehensive comma course you will find.
Uh oh, what happened here? There's the coordinating conjunction so, and the word that follows it, so why is there a comma before so that here? Well... I'll tell you why. In this sentence, so that is not combined to form a subordinating conjunction, and it is not used in place of in order that here. In this sentence, so is used as a coordinating conjunction joining two separate independent clauses, so Rule #1 applies. In this sentence, the word that is used as the subject of the clause and not in combination with so. That is why this is the most complete and comprehensive comma course you will find is an independent clause. So don't think that just because so and that are next to each other, it is automatically an example of Exception #1xa and takes no comma.


Exception #1xb: Independent Clauses Joined by Subordinating Conjunctions
Do not use a comma when a Subordinating Conjunction joins independent clauses (usually).

These are NOT Coordinating Conjunctions, so what we say about Coordinating Conjunctions' roles in a sentence and their punctuation placement does not apply to these words. That does not mean we NEVER use a comma before Subordinating Conjunctions that join independent clauses, but usually no comma would go before them. Subordinating Conjunctions are when, whenever, while, before, after, since, until, as, as soon as, as long as, where, wherever, if, unless, provided, so that, in order that, once, because, like (when used in place of as), and many more.

Be careful with some Subordinating Conjunctions such as as if, like (when used in place of as if), as though, though, although, whereas, no matter how, and even though. These are the exceptions, and a comma is needed before them because they usually introduce non-essential information.

Here is a link listing more Subordinating Conjunctions:
http://englishplus.com/grammar/00000377.htm


Examples of Independent Clauses Joined by Subordinating Conjunctions:

I hate to waste a single crumb of Mom's salmon patties because they are expensive and time-consuming to make.

The bowl of chili is delicious since it is hot.

McGregor refuses to eat dry cat food unless it is mixed with tuna.

McGregor loves having his head scratched as long as you don't touch his tail.

The chili is so thick you can eat it with a fork if you want to.

McGregor terrorizes the poodle next door before he visits the old German shepherd across the street.

McGregor is finicky until I add catnip to his lobster bisque.

McGregor runs through the house, even though he is sixteen years old.
Wait! Why is that comma before the Subordinating Conjunction even though?
Remember, I said Subordinating Conjunctions usually don't take a comma before them. The Subordinating Conjunction even though is one of a few exceptions to this rule, and a comma is needed before it.

I talk to the cat all day, as if he can understand me.

I talk to the cat all day, like he can understand me.

I talk to the cat all day as best friends would do.

I talk to the cat all day like best friends would do.


You can see more about comma usage with Subordinating Conjunctions by going to this excellent site:
http://hkrauthamer.tripod.com/Comma_rules.html
I suggest that you keep this link handy. I use it constantly.


Exception #1xc: Short Independent Clauses Joined by Coordinating Conjunctions
Under certain circumstances, the comma before the coordinating conjunction joining two independent clauses may be left out. If the first clause is short (5 - 6 words), especially if the two clauses are very closely related, you don't need the comma.

Examples of Short Independent Clauses Joined by Coordinating Conjunctions:

Bob tossed his poetry book and I caught it.

Bob tossed his poetry book all the way across the crowed library, and I caught it.
You have to use a comma here because the first clause is NOT short, so Rule #1 applies.

Winnie tried to bathe Lucy but the cat clawed her way free.

Pat carries a chainsaw so I'd knock before entering her house!

Bob wears a cap for he must protect his hair from the wind.

Danny must hurry or he will get smacked again with Winnie's Ruler!

In each of these examples above, the first independent clause is short (five words or less), and the two clauses are closely related to each other. Therefore, you can use the comma if you prefer, but you also have the option of omitting it.


Exception #1xd: Clauses and Phrases Joined by Coordinating Conjunctions
If an independent clause and a non-independent clause (a phrase) are joined by a coordinating conjunction, no comma is needed before the conjunction.
A non-independent clause, also known as a phrase, cannot stand alone as a separate sentence.

Examples of Clauses and Phrases Joined by Coordinating Conjunctions:

New Horizons Academy offers courses in writing techniques and hires only the best instructors.
In this sentence, the second part of the sentence is not an independent clause. It has no subject. Hires only the best instructors cannot stand alone as a complete sentence. It is a phrase. No comma is used before the Coordinating Conjunction and.

Lucy broke her leg and had the bone set, yet she walks normally.
Here, we have two independent clauses with a phrase in the middle. Had the bone set is a phrase. It can't stand alone as a separate sentence, so no comma goes before the Coordinating Conjunction and. But we need a comma before the Coordinating Conjunction yet because what follows (she walks normally) is an independent clause.

Danny taught eighth-grade English grammar for thirty years before he retired but doesn't miss it at all.
In this sentence, the second part of the sentence is not an independent clause. It has no subject. Doesn't miss it at all cannot stand alone as a complete sentence. It is a phrase. No comma is used before the Coordinating Conjunction but.


Exception #1xe: Clauses and Phrases Joined by Coordinating Conjunctions Expressing Extreme Contrast
A comma IS used before the coordinating conjunction (usually only yet and but) joining a clause to a phrase when expressing extreme contrast.

Examples of Clauses and Phrases Joined by Coordinating Conjunctions Expressing Extreme Contrast:

This is an easy rule, but difficult to remember.
Here, the second part of the sentence is not an independent clause. Difficult to remember cannot stand alone as a complete sentence. However, a comma is needed before the Coordinating Conjunction but because it is being used to express the extreme contrast between easy and difficult.

The Comma Sense students are experienced writers, yet inexperienced comma users.
A comma is needed before the Coordinating Conjunction yet because, even though what follows the coordinating conjunction is a phrase, it is being used to express the extreme contrast between experienced and inexperienced.

Don't be misled into thinking that all sentences containing the coordinating conjunctions but and yet automatically follow the Extreme Contrast Rule. They do not always express extreme contrast as is seen in that last example above for Exception #1xd.

More Examples of Rule #1 and Its Exceptions:

The volcano filled the sky with acrid smoke [1xd] but never erupted.
No comma goes before the Coordinating Conjunction because what follows is a phrase. Never erupted cannot stand alone as a complete sentence. Notice this example does NOT express extreme contrast.

Bob is armed with jelly beans [1xd] and ready to defend himself.
No comma goes before the Coordinating Conjunction because what follows is a phrase.

Winnie is an amazing instructor who spends time with each student, [1] so all of you should make an A+ this term.
This sentence contains two independent clauses joined by a coordinating conjunction. You need a comma here.

Sue studies all the comma usage rules carefully [1xa] so that she will earn a good grade.
This is an exception to Rule #1. The two independent clauses are joined by so that which is a subordinating conjunction. No comma goes here.

Sue studies all the comma usage rules carefully, [1] so that is why she earns a good grade.
This is not an example of Exception 1xa. You need a comma here. In this example, so and that are not combined to form a subordinating conjunction inferring in order that. So is the coordinating conjunction, and that is the subject of the verb is.

* George was brought in to maintain order in the class, [1] yet he is distracted by his crush on Marcia.
This sentence contains two independent clauses joined by a coordinating conjunction. You need a comma here.

The class is difficult [1xb] because there are many exceptions to the rules, [1] and Charlie has to think.
This sentence contains three independent clauses. The first two clauses are joined by the Subordinating Conjunction because and the second and third clauses are joined by the Coordinating Conjunction and. No comma goes before the Subordinating Conjunction, and a comma is needed for the Coordinating Conjunction. See? Are you beginning to understand this stuff?

This clause is short [1xc] so you don't need a comma.
The two independent clauses are joined by a Coordinating Conjunction, but the first clause is short, so the comma is optional.


Rule #2: Introductory Adverbial Clauses
Use a comma after an Introductory Adverbial Clause.

Introductory Adverbial Clauses are dependent clauses that provide background information or set the stage for the main part of the sentence. Introductory Adverbial Clauses start with Subordinate Conjunctions like the following:
after, although, as, because, before, every time, if, since, though, until, when, etc.
For a list of more Subordinating Conjunctions and their uses in Introductory Adverbial Clauses, go to:
http://englishplus.com/grammar/00000377.htm
http://ajaja.paradoxinc.org/Advanced/Writing/AdverbClauses.html
They are called Adverbial Clauses because, even though they don't start with an Adverb, they modify the main part of the sentence, so the whole clause acts as an adverb. They are also known as Subordinate Clauses.

What makes it a dependent clause is the fact that it is dependent on the subordinate conjunction that starts it. But without the beginning word, it can stand alone as an independent clause, a separate and complete sentence on its own.
   Let me repeat that. Without the beginning word, it can stand alone as an independent clause, a separate and complete sentence on its own. If the introduction to a sentence CANNOT stand on its own as a complete sentence, it is NOT an Introductory Adverbial Clause. It is an Introductory Phrase which we will study in the next lesson.

Examples of Introductory Adverbial Clauses:

If it is dark and cloudy today, Winnie and her vampire may go out for a picnic.
Notice, if you drop the subordinate conjunction if, which begins the clause, you have an independent clause which can stand on its own. It is dark and cloudy today is an independent clause.

* After Bob ate supper, he went to his desk and wrote a poem.

Since Pat wants to win the marathon, she walks ten miles a day.

Because he kept barking insistently, Winnie threw the ball for Buster.

Bob and Pat are going gopher hunting, but if they spot George, they must not shoot.
An Introductory Adverbial Clause does not necessarily begin a sentence. Remember, it introduces another independent clause, so it can appear in the middle of a sentence, and a comma should follow it. Here we have two independent clauses joined by a coordinating conjunction, so we need a comma before but. We also have an Introductory Adverbial Clause in the middle of the sentence. If they spot George introduces the independent clause they must not shoot, so we need a comma after this Introductory Adverbial Clause. Don't confuse this with what we said earlier about commas surrounding a Non-Essential Phrase after a Coordinating Conjunction. An Adverbial Clause is not a phrase, so no comma goes before it, only after it.
INCORRECT Bob and Pat are going gopher hunting, but, if they spot George, they must not shoot.
One of the most frequent errors in comma usage is the placement of a comma after a coordinating conjunction when an Introductory Adverbial Clause follows it. Don't do it. It's wrong.

ALERT!! The following sentence is NOT an example of Rule #2.
After grading her students' assignments, Winnie went for a walk.
Okay, you still need a comma here, but this is NOT an Introductory Adverbial Clause!!!!! If you drop the subordinate conjunction after, which begins the introduction, you DO NOT have an independent clause. Grading her students' assignments is NOT an independent clause. It cannot stand alone as a complete sentence. This is called an Introductory Phrase which we will study in the next lesson. Every term, most students attribute that comma in this sentence to Rule #2, and that is wrong, and I will mark it wrong on your homework.



Rule #3: Coordinate Adjectives
Use commas to separate two or more Coordinate Adjectives that precede the noun they modify.

Coordinate Adjectives are adjectives with equal (co-ordinate) status in describing the noun; neither adjective is subordinate to the other. You can decide if two adjectives next to each other are coordinate to each other by asking the following questions:
Does the sentence make sense if the adjectives are written in reverse order?
Does the sentence make sense if the adjectives are written with the conjunction and between them?
If you answer yes to these questions, then the adjectives are coordinate and should be separated by a comma.

Be careful here. If you place a coordinating conjunction like and or or between any of the adjectives, Rule #3 DOES NOT APPLY.

Examples of Coordinate Adjectives:

* Mr. Poe was a difficult, stubborn poet.
The poet was stubborn and difficult. These adjectives are Coordinate, equal in importance to poet, the noun they describe.

INCORRECT Mr. Poe was a difficult, stubborn, poet.
Never, never, ever separate the noun from its adjective!!

INCORRECT Mr. Poe was a difficult, and stubborn poet.
No, no, this is wrong. Since the coordinating conjunction and separates the adjectives difficult and stubborn, do NOT use a comma here.

The poet was difficult, opinionated, and stubborn.
This is not incorrect as far as comma placement is concerned. However, this is NOT an example of Rule #3. It is an example of Elements in a Series, which we will study next week. The adjectives do not precede the noun (poet) they modify, and the coordinating conjunction and has been injected into the list of adjectives, so the reference to coordinate adjectives is no longer relevant.

Bob has an easy, happy smile.
The adjectives are coordinate, equal in importance as they describe the noun smile. The smile was happy and easy.

The relentless, powerful, oppressive sun beat down on Pat's head.
The three adjectives are all coordinate. The sun was oppressive and relentless and powerful. The adjectives relentless and powerful are coordinate, so a comma goes between them. The adjectives powerful and oppressive are coordinate, so a comma goes between them.

The relentless, powerful, and oppressive sun beat down on Pat's head.
Commas are needed here, but not because of Rule #3. Rule #3 DOES NOT apply here because we used the word and to separate the third element is a series of three elements. The adjectives listed become Elements in a Series, a Rule we will study next week.

The relentless and powerful and oppressive sun beat down on Pat's head.
If you use and to separate EACH adjective, you don't use a comma between them.
Confused? Don't worry. I promise that this will all become clear to you very soon.


Rule #4: Non-Coordinate Adjectives
Do NOT use commas between Non-Coordinate Adjectives.

Non-Coordinate Adjectives are adjectives that are NOT equal in status in describing the noun. The adjective immediately next to the noun is superior to the adjective before it. It is so much a part of the noun which it describes that the Non-Coordinate Adjective and its noun are like one word, like a compound noun. Here are some examples of Non-Coordinate Adjectives and their nouns:
log cabin
German shepherd
magnifying glass
cell phone
adding machines
summer sun
jelly beans
rocking chair

If we were to put an adjective before these compound nouns, you would NOT put a comma between them because they wouldn't be equal in importance to the noun they modify.
white log cabin
old German shepherd
cracked magnifying glass
loud cell phone
huge adding machines
powerful summer sun
chocolate-covered jelly beans
sturdy rocking chair [not the motion of rocking but the type of chair]
old, blue, sturdy rocking chair [not the motion of rocking but the type of chair]
        
Ah, what happened here? Why the commas? Hmm... Let's see who is paying attention.
Go over to the forum and let's discuss this. It could mean extra credit for you.

Remember our little test with Coordinate Adjectives?
Does the sentence make sense if the adjectives are written in reverse order?
Does the sentence make sense if the adjectives are written with the conjunction and between them?
If you answer NO to these questions, then the adjectives are NOT Coordinate and should NOT be separated by a comma.

Examples of Non-Coordinate Adjectives:

* Betty lived in a white log cabin.
White and log are Non-Coordinate Adjectives. The log cabin was white. The adjective log is so much a part of the noun cabin that it is superior to the adjective white and is, therefore, Non-Coordinate—not equal in importance. No comma should separate white and log. Also, these adjectives fail the test for Coordinate Adjectives. You can't say the cabin was log and white. That doesn't make sense. So they can't be coordinate.

The relentless, powerful summer sun beat down on Pat's head.
Here, you have two Coordinate Adjectives (relentless and powerful) and Non-Coordinate Adjectives (powerful and summer). The sun was powerful and relentless, but you can't say the sun was summer and powerful—that sounds stupid. So summer is so much a part of the noun sun that it is not equal in importance to the adjective (powerful) next to it. Summer sun is almost like one word. It is superior. So no comma goes between powerful and summer.

Winnie couldn't finish her work because her loud cell phone kept ringing.

Buster adores that stupid, old German shepherd next door.

The beautiful, intelligent WDC reviewer is a kind and encouraging and helpful member of the community.
Whoa, what happened here? Let's break it down. Beautiful and intelligent are Coordinate Adjectives, so a comma is needed between them. Intelligent and WDC are Non-Coordinate Adjective, so no comma goes between them. The adjectives kind, encouraging, and helpful are EACH separated by the Coordinating Conjunction and, so no comma goes between them. Got it?


Rule #5: Non-Essential Elements
Use commas before and after Non-Essential (unnecessary) words, phrases, and clauses that are elements embedded in the sentence which interrupt the flow of the sentence but are not needed to clarify the meaning of the sentence.

Some elements of a sentence are non-essential and don't restrict the meaning of the sentence. That does not mean that Non-Essential Elements are bad things. They add much imagery, emotion, and characterization to your story. Non-Essential Elements are the salt and pepper of your sentences. These Non-Essential Elements can be words, phrases, or clauses, and comma placement around them is necessary. Many of these elements begin with relative pronouns like who, which, and that (That has its own rule). Some begin with participles (words ending in ing or ed). Some begin with prepositions like to, in, of, on, once, since, and many more. Some are infinitive phrases and begin with the infinitive to plus a verb like to be or to run or to study. Some are just names or adverbs. These Non-Essential Elements can be at the beginning, end, or in the middle of a sentence.

If you leave out the element or put it somewhere else in the sentence, does the essential meaning of the sentence change? If not, it is non-essential.

Here is a trick I learned to help me remember this rule: If the modifying element is non-essential, and you don't need it to understand the meaning of the sentence, put hooks (commas) around the element because it can easily be removed. See how simple that was?

Examples of Non-Essential Elements:

The average world temperature, surprisingly, has continued to rise.
The adverb surprisingly is a Non-Essential Word. You don't need the word surprisingly to understand the meaning of the sentence. You can easily remove it, so you need commas (hooks) surrounding it.
The average world temperature has continued to rise.
By the way, did you notice that the adjectives average and world are Non-Coordinating?

* Pat, the leader of Showering Acts of Joy, writes poetry and short stories.
The leader of Showering Acts of Joy is a Non-Essential Phrase. You don't need to know that Pat is the leader of Showering Acts of Joy to understand that she writes poetry and short stories. It is not Essential to know this, so commas need to surround this Non-Essential Element.
Pat writes poetry and short stories.

Winnie's Comma Sense students are beginning to learn proper comma placement, which is not taught much in school.
Which is a relative pronoun and often introduces a Non-Essential Element. The phrase at the end of the sentence is kind of like an afterthought and not essential to the meaning of the sentence.

We hoped that decorating the top of Cindy's cupcake with a dead grasshopper would freak her out, but, to our surprise, she just popped the whole thing in her mouth.
Here, we have a compound sentence with a coordinating conjunction, so we need a comma before but. We also have a Non-Essential phrase in the middle of the sentence. To our surprise is a prepositional phrase, and it is not important to the meaning of the sentence, so commas need to surround it.

Your best friends, where are your buddies when you need them?
The Non-Essential Element in this sentence is called an Absolute Phrase which we will study in Lesson #3 where it will acquire its own Rule Number [Rule #16].

My favorite uncle, who is eighty years old, walks three miles every day.
I only have one favorite uncle. Therefore, it is not essential to know that he is the one who is eighty. You can easily omit the element and still understand the sentence.
My favorite uncle walks three miles every day.

George, armed and at attention, monitors the Comma Sense Class each term.
The element armed and at attention adds imagery and characterization to George the gopher, but this information is not vital to the rest of the sentence. This particular Non-Essential Element is a Participial Phrase in the middle of the sentence.
George monitors the Comma Sense Class each term.

Those basketball shoes, to be perfectly honest, do not complement the suit you are planning to wear to the interview.
Here, we have a Non-Essential Element which is an infinitive phrase. To be perfectly honest interrupts the sentence and can be easily removed. We will learn more about interrupters in Lesson #5.

I am confused about some comma-placement rules, such as Appositives and Absolute Phrases.
We can use such as to introduce examples of something we mention. We normally use a comma before such as when we present a non-essential list of examples.
http://dictionary.cambridge.org/us/grammar/british-grammar/such-as


Rule #6: Essential Elements
Do NOT use commas to set off Essential Elements that are vital to the meaning of the sentence.

Some modifying elements of a sentence are essential, restricting the meaning of a modified term (usually the noun immediately next to the modifying element). No commas are used to surround them because they are a necessary part of the sentence. We wouldn't understand who or what the author is referring to if we were to omit these Essential Elements. Many of these elements begin with relative pronouns like who, which, and that (That has its own rule). Some begin with participles (words ending in ing or ed). Some begin with prepositions like to, in, of, on, except for, once, since, while, and many more. Prepositional phrases are almost always essential. Some are infinitive phrases and begin with the infinitive to plus a verb like to be or to run or to study. Some are just names or adverbs.

If you leave out the element or put it somewhere else in the sentence, does the essential meaning of the sentence change? If so, the element is essential.

Examples of Essential Elements:

The person checking tickets at the counter asked for a form of identification.
Checking tickets at the counter is an Essential Phrase, so no commas are used here. You need to know the person asking for a form is the one checking tickets. If you left out the essential phrase, the reader would be lost.
The person asked for a form. The reader is left with the question: What person?

The uncle who is eighty years old walks three miles every day.
I have four uncles. It is essential to know which uncle we are referring to, so we are talking about the one who is eighty, and you wouldn't use commas because the element is essential. Don't be confused into thinking that it is essential to know that an eighty-year-old can, amazingly, walk three miles. The essentiality factor of the element is based on the modified term the uncle which is positioned immediately next to the element who is eighty years old. If you left out the element, the sentence would be confusing.
The uncle walks three miles every day. Which uncle are we talking about here?

* The woman who interviewed you is my sister.
Who interviewed you is an Essential Phrase and no commas should surround it. The reader needs to know which woman is your sister.
The woman is my sister. Which woman is your sister?

The sixth-century philosopher Boethius was arrested, tortured, and bludgeoned to death.
Boethius is an Essential Word. We need to know which 6th century philosopher the writer is referring to.
The sixth-century philosopher was arrested, tortured, and bludgeoned to death. We need a name here. Which philosopher?

Winnie went to the supply room to get a new ruler.
Here, we have an Essential Element which is an infinitive phrase. It is essential because it finishes the sentence by explaining why she went to the supply room. No comma should precede it.

Buster hid under the bed when he heard the thunder.
Under the bed is a prepositional phrase. It is essential to know where Buster hid, so no commas are used. Prepositional phrases are almost always essential elements.

Winnie liked the purple hat except for the red feather on the top.
Except for the red feather and on the top are prepositional phrases. It is essential to know that Winnie had an exception to liking the hat and that it was the particular red feather on the top. Prepositional phrases are almost always essential.

I am confused about some comma-placement rules such as Appositives.
We can use such as to introduce an example of something we mention. Where there is just one essential example, we don’t use a comma.
http://dictionary.cambridge.org/us/grammar/british-grammar/such-as



Rule #7: Essential That Clauses
Do NOT use commas to set off Essential That Clauses.

That Clauses are dependent clauses beginning with the relative pronoun that. Even though they are called clauses, they can't stand alone as an independent sentence. They are also called Relative Clauses. That Clauses always immediately follow the noun or verb they are modifying and are always Essential. No comma is used to separate an Essential That Clause from the rest of the sentence.
Attention!! This also applies if the word that is implied.

Examples of That Clauses:

* The book that I borrowed from Pat is excellent.
That I borrowed from Pat is an Essential That Clause. Don't cut it off from the rest of the sentence with commas.

The book I borrowed from Pat is excellent.
The word that is not visible, but it is implied, so no commas should surround the Essential That Clause. [That] I borrowed from Pat is an Essential That Clause.

The apples that fell off the tree that was growing by the side of the road hit Bob in the arm that held the gun.
I know, I know, this sentence is terribly constructed. But I wanted to show you that you can have multiple Essential That Clauses in one sentence.

He was so tired that he couldn't do his Comma Sense homework.
She was so hungry that she ate all the unused commas before dinner.
She was so hungry [that] she ate all the unused commas before dinner. [That is implied]
Sometimes, so and that work together as a team—so being used as a qualifier, and the That Clause is used as a compliment to that qualifier. So...That is structured by using so plus an adjective and that plus a clause (or when that is implied). No comma is used before the That Clause. Don't confuse this combination of so...that with Exception #1xa where the words so and that are right next to each other to form a subordinating conjunction.

Don't make the assumption that just because the word THAT is in a sentence, it automatically introduces an Essential That Clause. Besides acting as a relative pronoun introducing a relative clause such as what we are learning about here in Rule #7, the word that can also act as many other parts of speech.
Here is a link explaining the many uses of the word that.
http://www2.gsu.edu/~eslhpb/grammar/lecture_13/that.html

Examples of That Acting as Different Parts of Speech:

That is not a nice cat.
Here, that is a pronoun and the subject of this sentence.

That cat just clawed my arm to shreds.
Here, that is an adjective modifying cat.

I need to bandage my arm so that it stops bleeding.
Here, that, used with so, is a subordinating conjunction. [1xa]

I didn't know that that cat was that vicious.
The first that acts as a relative pronoun introducing a noun clause. When a verb is followed by that plus a clause, the that + clause combination is called a noun clause because it functions like a noun as the direct object of the verb. Grammar books also discuss the structure as a "verb complement" because the that + clause "completes" the meaning and structure of the verb.
The second that is an adjective modifying cat.
The third that is used as an adverb modifying vicious.



RULES OF COMMA USAGE FOR LESSON #1:

LESSON #1
Rule #1 - Independent Clauses Joined by Coordinating Conjunctions (use commas)
>>Exception #1xa: Independent Clauses Joined by So That (don't use commas)
>>Exception #1xb: Independent Clauses Joined by Subordinating Conjunctions (don't use commas-usually)
>>Exception #1xc: Short Independent Clauses Joined by Coordinating Conjunctions (don't use commas)
>>Exception #1xd: Clauses and Phrases Joined by Coordinating Conjunctions (don't use commas)
>>Exception #1xe: Clauses and Phrases Joined by Coordinating Conjunctions Expressing Extreme Contrast (use commas)
Rule #2 - Introductory Adverbial Clauses (use commas)
Rule #3 - Coordinate Adjectives (use commas)
Rule #4 - Non-Coordinate Adjectives (don't use commas)
Rule #5 - Non-Essential Elements (use commas)
Rule #6 - Essential Elements (don't use commas)
Rule #7 - Essential That Clauses (don't use commas)

Click this item for list of parts of speech list: "Parts of Speech for Comma Sense Class" 





Instructor: Winnie Kay


Resource Links for this Lesson:
http://owl.english.purdue.edu/owl/resource/607/02/
http://grammar.ccc.commnet.edu/Grammar/conjunctions.htm
http://www.chompchomp.com/terms/coordinatingconjunction.htm
http://users.wirefire.com/tritt/tip18.html
http://englishplus.com/grammar/00000377.htm
http://hkrauthamer.tripod.com/Comma_rules.html
http://ajaja.paradoxinc.org/Advanced/Writing/AdverbClauses.html
http://dictionary.cambridge.org/us/grammar/british-grammar/such-as
http://www2.gsu.edu/~eslhpb/grammar/lecture_13/that.html
http://www.chompchomp.com/terms/preposition.htm