What the task is
You are shown an online class discussion. A professor has posed a question, and two students have already replied. You write a post that contributes to it.
The framing matters. This is not an essay question that happens to have context attached. It is a conversation you are joining, and responses that ignore the two existing posts are answering a different task from the one set.
An effective response generally runs to at least 100 words. There is no maximum.
What the 100 words actually means
The figure is a floor, not a target, and the reasoning behind it is worth understanding. Below roughly 100 words there is simply not room to state a position, support it, and show any range of grammar and vocabulary, so short responses tend to score low for structural reasons rather than because a rule was broken.
It does not follow that longer is better. There is no upper limit, but nothing is awarded for length, and writing a fourth paragraph consumes the time that reviewing the first three needed. Quality of contribution is what is valued.
The practical target is: enough words to develop one idea properly, then stop and check.
A worked example
A discussion in the task's style, written for this guide.
«Professor: We've been looking at how cities manage transport. Some argue that making public transport free would do more to reduce car use than any other single measure. Others think the money would be better spent improving reliability. What do you think?
Mira: Free travel is the clearest signal a city can send. Cost is the first thing people weigh, and removing it entirely changes the default choice.
Tomas: I'd rather have a service that turns up. I would pay more for a bus I could rely on than take a free one that might not come.»
And a response written for this guide.
«Tomas is closer to right, but I don't think reliability and cost are really competing. They just matter to different people.
Mira's argument works for anyone already close to deciding. If someone is weighing a bus against driving and the difference is marginal, removing the fare tips them over. But that describes people who already have a usable service. For everyone else, a free bus that comes twice an hour is still not a real alternative to a car, and no fare reduction fixes that.
What I'd add is that the two measures fail differently. Poor reliability loses passengers permanently, because people who are let down once stop planning around the service. A fare, however unwelcome, doesn't have that effect, because people grumble and keep travelling. That asymmetry is why I'd spend the money on reliability first, and treat free travel as something you can add later once the service is worth using.»
Why it contributes rather than restates
It engages with both existing posts by name and by argument, agreeing with Tomas and granting what is right in Mira's position, and then explaining where each applies. That is what makes it a contribution to a discussion rather than an isolated answer.
Crucially it adds something neither student said: the point about the two failures being asymmetric, with unreliability losing passengers permanently. A post that only picks a side has not contributed; a post that introduces a new consideration has.
Why the position is clear
The first sentence commits, and the last one says what should be done. A reader knows where this writer stands without inferring it.
The most common weak response surveys both sides even-handedly and never commits. It often contains good English and still scores poorly, because the task asked for a contribution and received a summary.
Why it is the right length
It runs comfortably past the 100-word floor without padding, because it has one developed idea rather than three undeveloped ones. Every sentence advances the argument, with no restatement of the professor's question and no throat-clearing opener.
How to spend the time
Spend a moment choosing a position before writing, and choose the one you can support best rather than the one you actually hold. This is not a test of sincerity, and an argument you have a concrete reason for will always come out better than the one you privately prefer but cannot justify.
Then lead with it. Opening with your position means the rest of the post has something to develop, and it protects you against running out of time before arriving at a point.
Reserve the last stretch for review rather than for more content. Revising what is there is more valuable than adding a paragraph nobody asked for.
- Read both student posts, because they are part of the prompt.
- Pick the position you can support, not the one you hold.
- State it first, then develop one idea properly.
- Reference what the other students argued, by name.
- Stop before the time runs out and review.
Common mistakes
- Surveying both sides without committing to one.
- Ignoring the two student posts and answering the professor in isolation.
- Restating the question in different words as an opening paragraph.
- Using memorised phrases or a prepared essay frame, both of which are scored down.
- Padding toward a word count instead of developing one idea.
- Writing until the clock stops, leaving no time to review.
How to build the skill
Practise on topics you already have opinions about, but practise the shape rather than the content: position, reason, something the others missed. That structure is what transfers, and it works on any subject.
A useful exercise is to write two opposing posts on the same prompt. It breaks the habit of searching for the right answer and builds the more useful habit of finding the best available argument for a position.
Write in your own voice throughout. Prepared sentences are easy for a rater to spot and are penalised, and they also crowd out the specific reasoning that earns marks.
Frequently asked questions
How many words should my discussion post be?
At least 100. That is a floor rather than a target: below it there is rarely room to develop an idea, and above it length alone earns nothing.
Do I have to respond to the other students?
It is a discussion, so engaging with what they argued is what makes your post a contribution. Answering the professor in isolation is a weaker response.
Should I give both sides of the argument?
Take a position. Even-handed surveys that never commit are the most common weak response, and they often contain perfectly good English.
Can I use a prepared template?
No. Responses that appear to rely on memorised or formulaic language are scored down, and a template also displaces the specific reasoning that earns marks.
Does it matter whether I actually believe my position?
No. Choose the side you can support with a concrete reason, which will always produce a better post than the view you hold but cannot justify.
Sources and editorial method
Facts that can change were checked against the following official ETS pages on July 24, 2026. Explanations and study advice are original Academic English Hub editorial content.