Lesson video

Welcome to this lesson.

Compound sentences: using the comma rule.

The outcome for today's lesson is you can use a comma before 'but' and 'or' coordinating conjunctions in a compound sentence.

Our keywords that are going to get us to that learning are here.

My turn, your turn.

Main clause, coordinating conjunction, compound sentence, comma.

The definitions of these keywords are here.

A main clause is a group of words that contains a verb and makes complete sense.

A coordinating conjunction is a word that joins two main clauses to form a compound sentence.

A compound sentence is a sentence formed of two main clauses and a joining word.

And a comma is a punctuation mark used before 'but' or 'or' coordinating conjunctions in a compound sentence.

Our lesson outline for today looks like this.

We'll start with the coordination comma rule.

Then we'll move on to rules of compound sentences.

Let's start with the coordination comma rule.

Let's start by listening to some compound sentences.

Our stomachs begin to digest our food, but other organs are also important.

A human's stomach contains acid, but it is a safe acid.

Stomachs can make noises, but these noises do not always mean we are hungry.

These three examples are compound sentences because they are formed of two main clauses joined with a coordinating conjunction.

Now you will remember main as our superstar clause.

Main clause is a group of words that contains a verb that makes complete sense.

Main is very confident because main doesn't need anything else to make complete sense.

In these examples, 'but' is used to join together two main clauses which are a positive and a negative main clause.

But what punctuation do you notice is working in each of my examples? Each sentence has a capital letter and a full stop to signal the start and end of the sentence.

But what other punctuation do you notice? That's right.

All of these compound sentences include a comma and I have made the commas purple in these examples of the same sentences to make the commas even clearer.

Our stomachs begin to digest our food, comma, but other organs are also important.

Hmm.

Where is the comma placed in this first example? Let's have a look at the second example.

A human stomach contains acid, comma, but it is a safe acid.

The comma is in the same place, it has come before 'but'.

Let's have a look at the third example.

Stomachs can make noises, comma, but these noises do not always mean we are hungry.

The comma comes before coordinating conjunction 'but' when it's joining two main clauses.

Commas are a very useful punctuation mark in English and you see them lots and lots in your reading books, in newspapers, in magazines, on websites for very different reasons.

Often commas have the job of separating clauses in sentences.

Remember, each main clause in a compound sentence is an equally important idea.

If you put the two main clauses on some grammar scales they would weigh the same because each clause is a main clause in a compound sentence.

If the coordinating conjunction 'but' is used, you need to write a comma before it in a compound sentence.

Let's have a look at some more examples.

A ferry is very heavy, comma, but it can float on water.

The comma comes before 'but' coordinating conjunction which is joining together two main clauses.

You're hungry now, but it is not lunchtime yet.

Puppies are born a certain colour, but they can change over time.

The comma separates the two main clauses and is placed before 'but'.

Let's check your understanding so far.

Which of these sentences is correct? A: You went to the sports shop, comma, but you didn't buy anything.

B: You went to the sports shop but you didn't buy anything.

Which is correct? That's right.

A is correct because we place a comma before but when it's working as a coordinating conjunction to join two main clauses, great job.

If the coordinating conjunction 'or' is used, you do need to write a comma before it in a compound sentence, just like with 'but'.

Let's have a look at this in action.

Here's my first main clause.

An engineer designs a ferry.

Here's my coordinating conjunction 'or', and you can see I've placed my comma before it.

Here's my second main clause.

It wouldn't be safe on water.

Here my second main clause is giving an option or an effect to my first main clause and that's why I've used conjunction 'or' to join.

I've remembered my comma before 'or'.

Let's have a look at another example.

I'll take an umbrella out with me, or I'll get soaking wet! Here I have two main clauses joined with comma 'or' coordinating conjunction.

The explorer could carry on hiking up the mountain, or she could take a pause.

Here I have two main clauses joined together with all coordinating conjunction with a comma placed before 'or'.

Remember, each idea in a compound sentence is equally important and weighs the same on the grammar scales.

Let's check.

Which of these sentences is correct? A: I'll eat a substantial breakfast or I won't have enough energy.

Or B: I'll eat a substantial breakfast, comma, or I won't have enough energy.

Which is correct? That's right, it's B.

We know that if we are using 'or' coordinating conjunction to join two main clauses, we place a comma before 'or'.

Great job.

And that word substantial is a brilliant word in this context.

It means a big healthy breakfast that is going to give enough energy for the day.

Great job, everyone.

Now, if the coordinating conjunction 'and' is used, you do not need to write a comma.

'But' and 'or' coordinating conjunctions do need a comma and coordinating conjunction does not need a comma.

And remember, 'and' is useful to build on from the first main clause to the second main clause in a compound sentence.

Let's see this in action.

A ferry floats on water and it can be used to transport heavy cargo.

I have two main clauses joined with 'and' coordinating conjunction and no need for a comma.

You must put your jacket on and you must get your warmest shoes.

Two main clauses joined with 'and', no need for a comma.

Lion cubs develop quickly after birth and they can start to walk at 10 days.

Two main clauses join together with 'and' coordinating conjunction and no need for a comma.

And remember, each idea in a compound sentence is an equally balanced main clause.

Let's check your understanding.

Which of these sentences is correct? A: Dragonflies are expert fliers, comma, and they can hover like helicopters.

Or B: Dragonflies are expert fliers and they can hover like helicopters.

Which is correct? That's right, it's B.

We know that if 'and' coordinating conjunction is used to join two main clauses in a compound sentence we do not need to use a comma.

Great job everyone.

So now I would like you to put all of this learning into practise.

For task one, I would like you to write a compound sentence with 'comma but' coordinating conjunction using this sentence stem.

Your first main clause is, an aeroplane is very heavy.

You need to stretch that first main clause using 'comma but' and a second main clause.

Remember, 'but' is really useful to join a positive to a negative main clause.

Pause the film now and write your compound sentence.

Great work.

Now I'd like you to check your sentence.

Does your sentence include two main clauses? Does your sentence include comma before 'but' coordinating conjunction? Does your sentence give a positive idea with a negative idea? Read your sentence back.

Check it carefully and edit any errors.

Pause the film now.

Great job.

Here are some example sentences I wrote for you.

An aeroplane is very heavy, comma, but it can fly.

Here's my second example.

An airplane's wings can flap, comma, but they are safely attached to its body.

And my third example.

Aeroplanes are an efficient way to travel, comma, but they are harmful to the environment.

In all three of my examples I have two main clauses joined together with 'comma but'.

Great job.

For your second task today I would like you to write a compound sentence with 'comma or' coordinating conjunction using this sentence stem.

Your first main clause is: An aeroplane travels very fast.

You need to stretch this main clause with 'comma or' coordinating conjunction and a second main clause.

And remember, 'or' coordinating conjunction is so useful when you are giving an option or an effect in your second main clause.

Pause the film now and write your compound sentence.

Great job.

Now I'd like you to check your sentence.

Does your compound sentence include two main clauses? Does it include 'comma' before 'or' coordinating conjunction? And does your sentence give an option or an effect in the second main clause that links to the first main clause? Read your sentence back.

Check it carefully and edit any errors.

Pause the film now.

Great job.

Here are some example sentences I wrote for you.

An aeroplane travels very fast, comma, or it wouldn't be able to take flight.

And my second example: Aeroplanes are designed by specialists, comma, or they wouldn't be safe to fly.

And my third example: You might like travelling by aeroplane, comma, or you might prefer travelling by boat.

In all three of my examples I have two main clauses joined together with 'comma or' to give a second option or effect to my first main clause.

Great job, everyone.

For task three today, I'm sure you've already guessed it.

I'd like you to write a compound sentence with 'and' coordinating conjunction using this sentence stem.

The airplane's tail helps it balance.

You need to stretch this first main clause with 'and' coordinating conjunction.

Remember, no comma and a second main clause.

Pause the film now and write your compound sentence.

Great work.

Now I'd like you to check your sentence.

Does it include two main clauses? Does it include 'and' coordinating conjunction? And does your second main clause build on your first main clause? Read your sentence back, check it carefully and make any edits.

Pause the film now.

Great work.

And here are some example sentences.

The airplane's tail helps it balance and its wings allow it to change direction.

And in the second example: Aeroplanes can travel long distances and they can carry a lot of passengers at once.

And in my third example: I've been on an aeroplane and I loved it.

You can see in my third example I've ended with an exclamation mark for emphasis of how much I loved the aeroplane.

Great job, everyone.

Now it's time to move to our second chunk of our lesson, rules of compound sentences.

Let's listen to some more compound sentences.

Panda bears eat bamboo and they sometimes hunt rodents.

Here I have a first main clause joined with 'and' coordinating conjunction to a second main clause.

Polar bears look white, but their skin is actually black.

Here I have a first main clause joined with 'comma but' coordinating conjunction to a second main clause, giving a positive and negative idea.

Don't get too close to a bull, or it might charge at you.

In this example I have a first main clause linked with 'comma or' coordinating conjunction to a second main clause that gives an option or an effect.

In each of these examples, there are two main clauses linked with a coordinating conjunction.

I've remembered my comma before 'but' and my comma before 'or'.

They are grammatically accurate and all my punctuation is accurate.

But what do you notice about the second idea that always comes in a compound sentence? Well, the second idea must be a full main clause in a compound sentence and it's so important that we master this now when you are learning about compound sentences and they're comma rules before you get any further through your sentence writing in school.

Let's have a look at the same examples again.

Here's my first main clause and my coordinating conjunction.

Panda bears eat bamboo and.

Now I could write leaves next.

Panda bears eat bamboo and leaves.

That would make a full simple sentence made of one main clause where 'and' is working as a conjunction to link two words.

But if I want to write a compound sentence my second idea must be a full main clause, like this.

They sometimes hunt rodents.

I don't want to get tricked and write a single word after my conjunction because if I do that it will not be working as a coordinating conjunction linking two main clauses.

Let's have a look at that second example.

Polar bears look white.

That's my first main clause, comma, 'but', coordinating conjunction, I must now write a second main clause to write a complete compound sentence like this.

Their skin is actually black.

I have a positive and a negative main clause joined with 'comma but'.

Don't get too close to a bull.

Here's my coordinating conjunction.

'Or', if I've written a comma before it and I've written my 'or' coordinating conjunction, I must make sure that what comes next is a full main clause and it is in my example: it might charge at you.

These are all examples of correct compound sentences because they are all formed of two main clauses joined with a coordinating conjunction.

Think of those equally balanced grammar scales to help you remember.

What goes on either side of the scales must be a full main clause if we are writing a compound sentence.

So let's check your understanding.

Which of these are true? In a compound sentence, A, there are at least two main clauses.

B, you use the conjunction 'because'.

C, each main clause holds equal weight.

D, you always write a comma.

Which are true in a compound sentence? Correct.

A and C are true.

In a compound sentence, there are at least two main clauses and each main clause holds equal weight.

We do not use the conjunction 'because' in a compound sentence we use 'and, but, or, or' coordinating conjunctions.

And we do not always write a comma because we know that before 'and' coordinating conjunction we do not write a comma.

We do before 'but and or' coordination conjunctions.

Great job, everyone.

For task four today, you are going to talk to your partner and tell them one reason why these are not compound sentences.

A, B, and C are examples of not compound sentences.

Why not? Pause the film now and tell your partner one reason.

Great job, everyone.

You're right.

They are not compound sentences.

These examples contain only one idea.

They are one main clause and so they're simple sentences, not compound sentences.

The second idea after 'and, but, or' conjunctions are not main clauses.

Ballet is not a main clause.

Not shark is not a main clause.

Not is not a main clause.

None of these are groups of words that contain a verb that make complete sense.

So none of these 'after, and, but, or' are complete main clauses.

And so none of these sentences are formed of two main clauses.

They are just formed of one main clause.

And we know that a sentence formed of one main clause is called a simple sentence.

Great job, everyone.

And for your final task today, you need to add the commas to these compound sentences.

Spot where the errors are and add the commas in.

Pause the film now as you complete the task.

Great job, everyone.

And you can see in A, no comma was needed because 'and' coordinating conjunction does not have a comma before.

In B: Dolphins eat squid but they do not eat shark.

We do have two main clauses working join together with 'but', so we need a comma before 'but' coordinating conjunction.

And in C: Do you enjoy going to the cinema or do you prefer going to the theatre? We have two main clauses.

Join together with 'or' coordinating conjunction.

We do place a comma before 'or'.

Great job, everyone.

So to summarise all our learning in today's lesson, we know compound sentences are formed of at least two main clauses.

We know that a coordinating conjunction joins two main clauses.

We know there are three coordinating conjunctions 'and, but, or', that's the most frequently used in English.

And we know that a comma is written before 'but' and 'or' coordinating conjunctions when it's joining two main clauses in a compound sentence.

Excellent work today.

Now remember, next, you need to go to your exit quiz for today's lesson to check and review all your learning and understanding of today's learning and I'm looking forward to seeing you next time.

Great job, everyone.