Expository writing can explain in several ways. Each way has a structure and signal words that tell the reader how the ideas relate.
| Structure | It answers | Signal words |
|---|---|---|
| Definition | What is it? | is, means, is called, refers to |
| Classification | What kinds are there? | types, kinds, groups, categories |
| Process | How does it happen or how is it done? | first, next, then, finally |
| Compare and contrast | How are they alike and different? | both, similarly, however, unlike |
| Cause and effect | Why does it happen? What results? | because, so, as a result, leads to |
Key idea
Explain by definition, classification, process, compare and contrast, or cause and effect. Choose the structure that answers your reader’s question, and use its signal words.
Why it works
Each structure matches a question a reader might ask. Signal words tell them in advance what kind of answer is coming, so they know whether to look for steps, for differences or for reasons.
Worked example: Name the structure
“Frogs and toads are both amphibians. However, frogs usually have smooth, damp skin, while toads have dry, bumpy skin.”
- Signal words: both, however, while.
- It shows how two things are alike and how they differ.
Answer: Compare and contrast.
Worked example: Match the question
A reader asks, “Why did the creek flood?” Which structure answers?
- “Why” asks for causes.
- The answer will give causes and their effect: heavy rain, so the creek rose.
Answer: Cause and effect.
Worked example: Classification
A paragraph begins: “Clouds come in three main types: cirrus, cumulus and stratus.” What structure will it use, and what will each sentence after it do?
- “Types” is a classification signal.
- Each following sentence will describe one type and what sets it apart.
Answer: Classification: one type per sentence or group of sentences.
Common mistake
Mixing structures in one paragraph without signal words, so the reader can’t tell whether they are reading steps, differences or causes. A longer piece may use several structures, but give each its own paragraph and its own signals.