TOEFL and the Duolingo English Test both require written English, but the writing is distributed across different communicative situations. The updated TOEFL iBT includes Build a Sentence, Write an Email, and Write for an Academic Discussion. The Duolingo English Test can require writing about visual or verbal prompts, extending an answer in Interactive Writing, and producing a writing sample.
This comparison focuses on vocabulary use: audience, purpose, evidence, development, and lexical control. Start with the TOEFL vocabulary hub or Duolingo English Test vocabulary hub to practice inside the correct task route.
Shared foundations
Both tests reward writing that is:
- relevant to the prompt;
- specific enough to support its claims;
- organized around clear relationships;
- accurate in word form and collocation;
- calibrated for certainty and scope;
- developed with examples or explanations rather than filler.
The highest-value vocabulary is functional:
- purpose: I am writing regarding…;
- position: I would argue that…;
- addition: A further consideration is…;
- qualification: to some extent, provided that, in many cases;
- evidence: suggests, indicates, is associated with;
- consequence: can lead to, may result in;
- contrast: whereas, however, even though.
These expressions matter because they organize meaning, not because they look advanced.
Task-purpose map
| Writing job | TOEFL | Duolingo English Test |
|---|---|---|
| Construct a grammatical sentence | Build a Sentence | completion tasks can require form control, but not the same named task |
| Practical communication | Write an Email | can arise in prompt-based responses, but not as the same task |
| Join a discussion | Academic Discussion | interactive and extended responses can require development |
| Describe visible evidence | not the focus of current writing tasks | photo-based writing |
| Extend earlier ideas | respond to a discussion thread | Interactive Writing follow-up |
| Shared response | scored writing task | writing sample shared under the provider’s process |
Do not carry a complete template across these jobs. Carry the vocabulary decisions.
In TOEFL Build a Sentence, vocabulary knowledge supports grammar rather than extended composition: keep collocations together, identify which form a slot requires, and preserve the order inside embedded clauses. Practice those decisions in Lyra Practice’s Build a Sentence collocation guide and question word-order guide.
TOEFL email vocabulary: person, purpose, action
A useful email opens with context and moves quickly to the requested outcome.
Weak:
“Dear Sir or Madam, I am writing this email to tell you about a very unfortunate situation that has caused many inconveniences.”
Specific:
“Hello Professor Lee, I am writing about the laboratory session moved to Friday. I have a required seminar at the same time, so could I attend the Tuesday section instead?”
The second version identifies recipient, event, conflict, and request. Useful phrases include:
- Could you clarify whether…?
- Would it be possible to…?
- The revised schedule conflicts with…
- If that option is unavailable, I could…
- Please let me know which alternative you prefer.
Practice these through Lyra Practice’s TOEFL email tone guide, deadline clarification guide, and requests and solutions guide.
TOEFL academic discussion: contribute, do not announce
An academic discussion response should add a supported idea and, where useful, connect to another contribution.
Empty opening:
“This is a controversial topic in modern society, and both sides have advantages and disadvantages.”
Contribution:
“Maya is right that recorded lectures improve access, but recordings may also reduce attendance when students see them as a complete substitute for discussion. A better policy would combine recordings with small participation tasks.”
The second response acknowledges, qualifies, and proposes. It uses the existing conversation rather than delivering a generic essay introduction.
Use Lyra Practice’s TOEFL academic discussion agreement guide and counterargument examples to practice adding a new reason, exception, consequence, or criterion.
Understanding is only the first step.
Lyra Practice helps you retrieve and use high-value workplace expressions in realistic situations until they feel natural.
Start a practice session →DET photo writing: visible evidence first
Photo-based writing requires precise observation before interpretation.
Visible:
“Several passengers are waiting beneath a covered platform, and one person is checking the electronic display.”
Cautious inference:
“The display may be showing a delay because several people are looking toward it.”
Unsupported:
“The train was canceled after a mechanical failure.”
The photo may not show cancellation, cause, or earlier events. Useful vocabulary includes spatial prepositions, present-progressive actions, concrete nouns, and cautious inference.
Practice with Lyra Practice’s DET photo-writing guide and visible-evidence picture guide. Label each sentence seen, reasonably inferred, or invented.
DET Interactive Writing: extend instead of repeat
Interactive Writing asks you to continue developing your initial response. The follow-up creates a new job.
Initial idea:
“Universities should provide free public-transport passes because commuting costs can restrict access to classes.”
Repetition:
“I think transport passes should be free because commuting is expensive.”
Extension:
“The policy would be most effective if evening and weekend routes were included. Students with laboratory or work commitments often travel outside standard class hours, so a weekday-only pass would leave part of the access problem unresolved.”
The extension adds a condition, affected group, and consequence.
Use Lyra Practice’s Interactive Writing evidence guide and follow-up-question guide. Classify follow-ups as asking for a reason, example, limitation, implementation detail, consequence, or alternative.
Position and claim strength
Both tests punish meaning indirectly when vocabulary makes a claim indefensible.
Scale:
may help → tends to help → is likely to help → will help → guarantees
Choose according to evidence.
“Peer feedback can help writers notice unclear explanations.”
This is a reasonable possibility claim.
“Peer feedback guarantees perfect writing for every student.”
This is absolute and implausible.
Scope matters too:
- some students is not students generally;
- one contributing factor is not the sole cause;
- in this example is not in every case.
Use the claim-strength sections in Lyra Practice’s TOEFL and DET writing guides to revise one variable at a time: certainty, quantity, frequency, or causation.
Word families and collocation
Build productive families inside sentences:
- respond → response → responsive;
- clarify → clarification → clear;
- vary → variation → variable;
- justify → justification → justified.
Then attach natural patterns:
- respond to a concern;
- request clarification about;
- variation in results;
- justify a decision with evidence.
Do not rotate forms only to avoid repetition. “The policy has variation” may be less precise than “the policy varies by region.” Grammar and meaning choose the form.
Lyra Practice’s TOEFL writing vocabulary guide and DET writing vocabulary guide provide the task map; use their related guides to practice each pattern in context.
Cohesion without connector stacking
Weak:
“Firstly, technology is useful. Moreover, it is distracting. Furthermore, students use it. On the other hand, it is helpful.”
Controlled:
“Technology can widen access to course material. However, constant notifications may interrupt sustained reading, so schools should pair device access with settings that limit distractions.”
The second paragraph uses contrast and consequence because those are the actual relationships. Connectors do not create logic; they label it.
Track reference as well. This problem must point to a named problem. The latter option requires two clear alternatives. A paragraph that sounds connected but has ambiguous references is not cohesive.
A Lyra Practice two-route plan
For TOEFL Writing:
- Use the TOEFL writing overview.
- Practice Build a Sentence collocations and clause order.
- Practice email purpose, tone, and solution language.
- Practice academic-discussion agreement, qualification, and counterargument.
- Review word choice, collocation, form, and scope errors.
For DET Writing:
- Use the DET writing-by-question-type guide.
- Separate photo observation from inference.
- Practice short prompt development.
- Train Interactive Writing follow-ups that add a new dimension.
For both, practice reusable moves in the linked Lyra Practice task guides, not complete responses: state a constraint, give one example, qualify scope, request one action, add one implementation detail.
Sources
- TOEFL iBT Writing section — ETS
- Duolingo English Test official guide
- Duolingo English Test structure
- DET Write About the Photo
Related
- TOEFL writing vocabulary
- TOEFL Build a Sentence collocations
- TOEFL email requests and solutions
- DET writing vocabulary by question type
- DET Interactive Writing evidence
- DET photo-writing vocabulary
TOEFL is a trademark of ETS. The Duolingo English Test is a trademark of Duolingo. Lyra Practice is not affiliated with or endorsed by either provider.