B. Foundations of Language · Foundations: Speaking, Listening, Words and Fluency

Speaking Like an Expert: Domain-Specific Words and Cohesive, Coherent Sentences

B1.5 A3.1 A1.1About 45 minutes

Learning goals

I can choose precise, descriptive words, including domain-specific vocabulary from my other subjects.
I can define a technical term the first time I use it and then use it consistently.
I can link my spoken sentences with cohesive ties: clear references, transitions and the given-to-new pattern.
I can organize what I say so it is coherent: one main idea, in a logical order.
I can adjust my word choice and sentences so my audience understands.

Words to know

domain-specific vocabulary
Words that belong mainly to one subject or field, like viscosity in science or Confederation in history.

cohesive
Linked together smoothly, sentence to sentence, so listeners can follow.

coherent
Making sense as a whole: one clear main idea, in a logical order.

transition
A word or phrase that shows how ideas connect, like however, as a result or next.

reference
A word that points back to something already said, like it, they, this process.

given-to-new
A pattern where each sentence starts with something the listener already knows and ends with new information.

Remember from Grade 7

In Grade 7 you replaced vague words with precise ones, used adjectives and adverbs on purpose, varied your sentence types, made pronouns clear, used transitions, and chose the active or passive voice. Grade 8 adds two things: speaking with the domain-specific vocabulary of your subjects (the words experts use), and building sentences that are cohesive and coherent even when the topic is complex.

Let's start with two explanations

A student explains how a city cleans drinking water.

Version A: "So, the water goes in and they put stuff in it and it gets all clumpy and then it goes down and then they filter it and they add the other stuff and it's clean."

Version B: "Water from the lake is pumped into the treatment plant. First, the plant adds chemicals that make tiny particles stick together into clumps, called floc. Next, the floc sinks to the bottom of a tank; this step is called sedimentation. Then the water passes through filters of sand and gravel. Finally, the water is disinfected, often with chlorine or ultraviolet light, to kill germs."

Version B uses domain-specific words (floc, sedimentation, disinfected) and defines them. Its sentences are linked (First, Next, Then, Finally; the floc points back to clumps). You could draw the process from Version B. You couldn't from Version A.

Long concrete settling tanks filled with water inside a water treatment plant, with metal walkways, pipes and a lake view through the windows. — Settling tanks in a drinking water treatment plant. This is where the floc sinks to the bottom, one of the steps Version B explains with precise, domain-specific words. AI-generated image

Version B as a picture: each transition (First, Next, Then, Finally) starts a new step, and each step has its own domain-specific word.

Subject	Domain-specific words (Grade 8 examples)
Science: cells	cell membrane, nucleus, organelle, unicellular, multicellular
Science: fluids	viscosity, density, buoyancy, pressure
Science: water systems	watershed, groundwater, aquifer, runoff
Mathematics	square root, linear relation, rational number, scientific notation
Geography	population density, urbanization, settlement pattern, quality of life
History	Confederation, treaty, immigration, primary source
The Arts	crescendo (music), tableau (drama), contrast (visual arts)

When you speak about a subject, use its words. They're more precise than everyday words.

Using domain-specific words well

Define on first use, especially for a general audience: "Viscosity, which is how much a liquid resists flowing, is higher in honey than in water."
Then use it consistently. If you say viscosity and later thickness and later runniness, listeners may think you mean three different things.
Match your audience. Explaining to a Grade 4 student? Use the term, but add an everyday comparison: "Honey has high viscosity: it's slow and sticky."
Be precise, not fancy. Use a technical word because it says exactly what you mean, not to impress.

Cohesion: linking sentence to sentence

Listeners can't reread, so your sentences need ties:

Clear references: it, they, this, these must point to one clear thing. Even better, add a noun: this process, these cells, that treaty.
Transitions show the relationship: sequence (first, next, finally), cause and effect (because, as a result, therefore), contrast (however, on the other hand), example (for instance), adding (also, in addition).
Repeat key terms (don't swap them for synonyms when precision matters).
Given-to-new: start each sentence with something the listener already knows and end with something new. Then the next sentence picks up that new thing.

The given-to-new chain: each sentence ends with new information (blue), and the next sentence starts with it as known information (yellow). The arrows show the link.

Coherence: the big picture

Cohesion links sentences. Coherence is about the whole talk:

One main idea that everything supports. Say it near the start.
A logical order: time order for processes, cause before effect, most important point first (or last, for a big finish).
No detours. An interesting fact that doesn't support your main idea can confuse listeners.
Sentence variety, with control. Long sentences can show how ideas connect, but if you lose track mid-sentence, break it into two.

Worked example

Let's revise a spoken explanation

A student explains buoyancy for a science check-in:

"Things float. It depends. Like a boat is heavy but it floats. It's because of the water. It pushes up. A rock doesn't. So that's why."

Find the main idea. The student is trying to explain why some objects float and others sink. Say that first.
Add domain-specific words and define them. Buoyant force: the upward push from a fluid. Density: how much mass is packed into a certain volume.
Fix unclear references. It depends (on what?), It's because of the water (what about the water?), It pushes up (what does?).
Add transitions to show cause and effect and contrast: because, however, so.
Use given-to-new and put it in logical order: general rule → example that floats → example that sinks → conclusion.

"Whether an object floats depends on buoyant force, which is the upward push a fluid gives to an object in it. An object floats when the buoyant force is strong enough to hold up its weight. For example, a steel boat is heavy, but its hollow shape makes its overall density less than the water's, so the water's push holds it up. A rock, however, is denser than water, so it sinks. In short, floating depends on density, not just weight."

The "so what" check

After you explain something, ask a listener to say it back in one sentence. If they can't, look for a missing definition, an unclear reference (it, they, stuff) or a missing transition.

Just for fun

**Why did the science teacher ban the word stuff?**

Because it isn't domain-specific. It's every-domain-specific, and that's exactly the problem.

Hands-on activity

Expert explainer challenge

You need: a family member as your audience, a timer, paper and a pencil, and one object that connects to a subject (for example, a bottle of syrup and a glass of water for viscosity; a map for population density; a leaf for cells).

Choose a topic from science, math, geography or history that you know well.
Write three domain-specific words you'll use and a short definition for each.
Plan your order with transitions (first, because, however, as a result, finally).
Give a one-minute explanation using the object. Define each term the first time you use it.
Your listener makes a tally: one mark for each domain word, one for each transition, and a star each time they get confused (for example, an unclear it).
Ask your listener to say your main idea in one sentence. If they can't, revise and try again.

Safety: if you use food or liquids, do it over a tray or sink and clean up together.

What to look for: three domain-specific words, each defined on first use and used consistently; at least three transitions; clear references; and a listener who can sum up the main idea.

Your turn

What is domain-specific vocabulary? Give one example from science and one from history.

Fix the vague words: "The stuff in the cell controls things."

Why should you define a technical word the first time you use it?

Add a transition: The river flooded. The town built higher banks.

Make the reference clearer: "The scientist told the farmer that they were wrong."

What is the difference between cohesive and coherent?

Which transition shows contrast: therefore, however or next?

More practice: warm-up

Name one domain-specific word from math.

Name one transition for sequence.

Name one transition for cause and effect.

What does coherent mean?

Swap the weak word: "The water was very thick and slow." (Use a science word.)

More practice: on your own

Use given-to-new to link these: A watershed is an area of land. Rain and snowmelt drain from it into a river or lake.

A speaker says viscosity, then thickness, then gooiness. Why could this confuse listeners?

Explain population density to a Grade 4 student in one or two sentences.

Put these in a logical order for an explanation of how a bill becomes a law: it is debated; it is introduced; it receives royal assent; it is voted on.

Remove the detour: "Cells are the basic units of life. My cousin wants to be a doctor. All living things are made of one or more cells."

Challenge

Give a 4-sentence oral explanation of why ice floats on a lake in winter, using density and two transitions.

A student explains the water cycle using these words in this order: evaporation, clouds, rain, puddles, the sun heats water. What is wrong with the coherence, and how would you fix it?

Explain why a speaker should adjust the number of technical words for a panel of scientists versus a community meeting about the same water project.

Check your understanding

Quiz

Which sentence uses domain-specific vocabulary correctly?

Which word is a contrast transition?

A talk is coherent when...

What should you do the first time you use a technical word with a general audience?

Which pair shows the given-to-new pattern?

Which reference is clearest?

For parents and teachers

Big idea (B1.5, with A3.1 and A1.1): Grade 8 students use precise and descriptive word choice, including domain-specific vocabulary from various subjects, and cohesive and coherent sentences when they communicate orally, to support audience comprehension. Using subject vocabulary connects language with science, math, history and geography (A3.1).

How to help at home:

Ask your child to explain something from science or geography class to you as if you were new to it. Ask them to define each term.
Point out transitions in news reports: "Did you hear 'as a result'?"
When your child says it or stuff, ask gently: "Which thing?"

Common difficulties:

Using technical words without defining them, or swapping them for everyday words halfway through.
Run-on speech linked only with and then. Encourage pausing and choosing a more precise transition.
Detours. Interesting side facts are fine in conversation, but in an explanation they can hide the main idea.