B. Foundations of Language · Spelling, Grammar and Punctuation

Combining Sentences to Show How Ideas Are Related

B3.1 B3.2 A3.1About 45 minutes

Learning goals

I can choose a joining word that shows the relationship I mean: addition, contrast, cause, effect, time, condition or purpose.
I can combine short sentences using conjunctions and relative clauses.
I can use commas correctly when a dependent clause comes first.
I can vary my sentences so my writing is clear and interesting in any subject.

Words to know

coordinating conjunction
A word that joins two equal ideas: for, and, nor, but, or, yet, so (FANBOYS).

subordinating conjunction
A word that starts a dependent clause and shows how it relates to the main clause, like because, although, unless, until.

relationship
How two ideas are connected, such as cause and effect or contrast.

sentence combining
Joining two or more short sentences into one smoother sentence.

Remember from Grade 5

You can build simple, compound, complex and compound-complex sentences. You fixed run-ons and comma splices, and used correlative conjunctions like either...or.

In Grade 6, the focus is on choosing the right sentence form to show exactly how your ideas are related. The joining word you choose changes the meaning!

Same facts, different meanings

Look at these two short sentences: It was snowing. We went sledding.

It was snowing, so we went sledding. (cause and effect: the snow made sledding possible)
Although it was snowing, we went sledding. (contrast: we went anyway, as if the snow were a problem)
When it was snowing, we went sledding. (time)

The words so, although and when each tell the reader a different relationship.

A snowy hill in a park during snowfall, with small figures sledding and colourful sleds. — It was snowing, so we went sledding. Combining two short sentences with a joining word shows how the ideas are related. AI-generated image

Same two facts, three joining words, three different relationships: cause, contrast and time.

Relationship	Joining words	Example
Addition	and, also, as well as	Bees make honey, and they pollinate flowers.
Contrast	but, yet, although, while, whereas	Although bats fly, they are mammals, not birds.
Cause	because, since, as	Monarchs fly south because they can't survive Canadian winters.
Effect / result	so, therefore (with a semicolon or new sentence)	The weather turned cold, so the frogs hibernated at the bottom of the pond.
Time	when, after, before, until, while, as soon as	After the sap starts to flow, farmers collect it.
Condition	if, unless, whether	Most plants won't grow well unless they get light.
Purpose	so that, in order to	We planted milkweed so that monarchs would visit.
Description	who, which, that, where, when	Little brown bats, which use echolocation, hunt at night.

Choose the joining word that shows the relationship you mean

Comma check

Dependent clause first? Put a comma after it: Because it was icy, school was cancelled.
Dependent clause last? Usually no comma: School was cancelled because it was icy.
Two independent clauses with FANBOYS? Comma before the conjunction: It was icy, so school was cancelled.

Where the clauses sit decides the comma. Bold shows the dependent clause or the joining word.

Worked example

Let's combine to show a relationship

Combine into one sentence that shows cause: The ice on the lake was thin. The skating party was cancelled.

Which happened first, and which caused the other? Thin ice caused the cancellation.
Choose a cause word: because or since.
Option 1 (dependent clause last): The skating party was cancelled because the ice on the lake was thin.
Option 2 (dependent clause first, add a comma): Because the ice on the lake was thin, the skating party was cancelled.

Either option works. Both clearly show cause and effect.

Worked example

Let's combine three sentences in science writing

Beavers build dams. The dams create ponds. Many animals live in the ponds.

Find a shared noun: ponds (and dams).
Turn one idea into a relative clause: ponds where many animals live.
Connect the rest: Beavers build dams that create ponds where many animals live.
Read it aloud. It's clear and not too long.

Beavers build dams that create ponds where many animals live.

Variety, not just length

Combining is powerful, but don't glue everything together. A very long sentence can lose the reader. Mix short sentences (for punch) with longer ones (to explain). Read your writing aloud: if you run out of breath, split a sentence.

Just for fun

What if you glued every sentence in your story together with and? You'd get one sentence that goes on and on and on and on, and your reader would need a snack break and a nap halfway through!

Hands-on activity

Relationship dice

You need: a paper cube (or a regular die and a chart), paper and a pencil.

Make a chart: 1 = because, 2 = although, 3 = when, 4 = unless, 5 = so that, 6 = which.
Write 5 pairs of short sentences about a topic from science or social studies, like Trees lose leaves in fall. Trees save water in winter.
Roll the die. Use that joining word to combine one pair. (If the word doesn't make sense with the facts, explain why and roll again.)
Check the commas.
Talk with a grown-up: how did the joining word change the meaning?
Choose your best sentence and add it to a piece of writing you're working on.

Your turn

What relationship does although show?

Combine to show time: We finished our homework. We went skating.

Combine to show condition: You can borrow my bike. You must wear a helmet.

Combine to show contrast: Penguins are birds. Penguins can't fly.

Add a comma if needed: Unless it rains we will play outside.

Combine with a relative clause: Mr. Tran is our crossing guard. He waves at every student.

Combine to show purpose: We put up a bird feeder. We wanted to watch chickadees.

More practice: warm-up

Name the seven FANBOYS conjunctions.

What relationship does because show?

What relationship does unless show?

Does a dependent clause at the start of a sentence need a comma after it?

Which word shows time: when or unless?

More practice: on your own

Explain the difference: (a) I'll go if you come. (b) I'll go because you're coming.

Combine to show effect: The power went out. We played board games by candlelight.

Combine with whereas to show contrast: Frogs have smooth, moist skin. Toads usually have dry, bumpy skin.

This sentence uses the wrong joining word. Fix it: We wore our warmest coats although it was −20°C.

Is this sentence too long? Split it into two or three clear sentences: We went to the market and we bought apples and then we went home and we made a pie and it was delicious.

Challenge

Combine all four into one or two clear sentences: Wetlands are important. Wetlands filter water. Many birds nest in wetlands. Some wetlands are being drained.

Combine The game was tied. We went home. in two ways: once with although and once with when. Explain how the meaning changes.

Write a compound-complex sentence about a season in Canada that shows two different relationships. Name them.

Check your understanding

Quiz

Which word shows contrast?

Which sentence shows cause?

Which sentence is punctuated correctly?

Which joining word shows purpose?

Most plants won't grow well ___ they get light. Which word fits best?

Which is the best combination of Bats are mammals. Bats can fly.?

For parents and teachers

Big idea (B3.1, B3.2): Grade 6 students use their knowledge of sentence types and forms to construct sentences that communicate ideas effectively, and they continue to use coordinating and subordinating conjunctions correctly. Using science and social studies facts shows how these skills help in every subject (A3.1).

How to help at home:

When your child writes a list of facts, ask: "How are these two facts connected? Which word shows that?"
Play "Same facts, new meaning": take two sentences and combine them with because, although and when.
Praise a mix of short and long sentences.

Common difficulties:

Using and for everything. Ask which relationship they mean.
Wrong relationship word (although when the meaning is because). Read it aloud and ask if it makes sense.
Overly long sentences. Encourage splitting when a sentence has more than two or three joining words.