Open and closed questions
Open and Closed Questions
Master the two most fundamental building blocks of every interview question — open and closed — and learn exactly when each one gathers the richest, most accurate evidence.
Introduction
Every question you ask in an interview is built from one of two basic shapes: it is either open or closed. This may sound simple, but the shape of your question controls the shape of the answer you get. Ask the wrong type at the wrong moment, and even a strong candidate will give you little to work with.
A closed question invites a short, specific answer — often just "yes," "no," or a single fact. An open question invites explanation, reasoning, and detail. Learning to choose deliberately between them is the first and most important skill in question design.
Learning Objectives
- Define open and closed questions.
- Explain the strengths and weaknesses of each.
- Choose the right type for a given purpose.
- Convert a weak closed question into a strong open one.
- Combine both types using the funnel technique.
Why This Matters
Interviewers often complain that a candidate "didn't say much." Frequently, the real cause is the question, not the candidate. A closed question like "Did you enjoy your project?" invites a one-word reply. An open question like "What did you enjoy most about your project, and why?" invites a rich, revealing answer.
Because open questions produce far more evidence, they are the backbone of evidence-based interviewing. But closed questions still have their place. Knowing which to use — and when — lets you control the flow and depth of the entire conversation.
What Is a Closed Question?
A closed question can be answered with a single word, a short phrase, or a specific fact. It narrows the response and is useful for confirming details quickly.
Examples of closed questions:
- "Do you know Python?"
- "How many years did you study computer science?"
- "Did you work in a team on that project?"
- "Which language did you use?"
What Is an Open Question?
An open question cannot be answered in a single word. It invites the candidate to explain, describe, reason, or tell a story, producing much richer evidence.
Examples of open questions:
- "How did you approach that project?"
- "What challenges did you face, and how did you handle them?"
- "Why did you choose that language?"
- "Tell me about your role on the team."
Think of Doors
A closed question is like a door that is only slightly ajar — a candidate can slip a quick answer through and it shuts. An open question swings the door wide, inviting them to walk through and show you everything inside.
Open vs Closed: Side by Side
| Aspect | Closed Question | Open Question |
|---|---|---|
| Answer length | Short — a word or fact. | Long — explanation or story. |
| Typical start | Do, did, is, are, how many. | How, what, why, tell me about. |
| Evidence gathered | Low. | High. |
| Best for | Confirming facts quickly. | Exploring reasoning and depth. |
| Risk | Little insight; feels like a quiz. | Can ramble if not focused. |
When to Use Each Type
Use Open Questions To...
- Explore how a candidate thinks.
- Draw out reasoning and detail.
- Assess competencies and behaviour.
- Open a topic for deeper probing.
Use Closed Questions To...
- Confirm a specific fact quickly.
- Check availability or logistics.
- Pin down a precise detail.
- Verify something before going deeper.
Converting Closed Questions Into Open Ones
One of the most useful skills is turning a weak closed question into a strong open one. Usually you just change the first word.
| Closed (Weak) | Open (Strong) |
|---|---|
| "Did you like the project?" | "What did you like about the project?" |
| "Was it difficult?" | "What made it difficult?" |
| "Did you fix the bug?" | "How did you fix the bug?" |
| "Do you work well in teams?" | "Tell me about a time you worked in a team." |
Combining Both: The Funnel Technique
Skilled interviewers do not choose one type forever — they combine them. The funnel technique starts wide with an open question, then narrows with closed questions to pin down specifics.
Start Open
"Tell me about a project you're proud of." — invites a rich, revealing answer.
Probe Deeper (Still Open)
"How did you handle the biggest challenge?" — explores reasoning.
Narrow With Closed
"Which language did you use?" — confirms a specific fact.
Worked Example: Two Interviews Compared
All Closed Questions
"Did you do a project? Yes. Was it in Java? Yes. Did it work? Yes." The interviewer learns almost nothing about the candidate's real ability.
Open, Then Closed
"Tell me about your project. How did you build it? What went wrong? Which language did you use?" The interviewer gathers a full picture, then confirms the details.
Best Practices for Using Question Types
- Default to open questions to gather rich evidence.
- Use closed questions to confirm facts, not to explore.
- Start "How," "What," "Why," or "Tell me about" for open questions.
- Convert weak closed questions by changing the first word.
- Use the funnel: open first, then narrow with closed.
- Avoid stacking many closed questions in a row like a quiz.
Common Mistakes
Avoid These
- Relying mostly on closed questions.
- Turning the interview into a yes/no quiz.
- Asking open questions so vague they ramble.
- Never confirming key facts.
- Accidentally embedding the answer in the question.
Do These Instead
- Lead with focused open questions.
- Keep the conversation exploratory.
- Make open questions clear and specific.
- Confirm key facts with closed questions.
- Keep questions neutral and answer-free.
Real-World Use Cases
Behavioural Interviews
Open questions like "Tell me about a time..." draw out full STAR stories, while a closed follow-up confirms a specific detail like the timeframe.
Technical Screening
"How would you approach this problem?" reveals reasoning; "Which data structure did you use?" pins down the specific choice.
Screening Calls
Closed questions quickly confirm availability and logistics, leaving open questions to explore motivation and fit.
Frequently Asked Questions
Are closed questions bad?
No. Closed questions are excellent for confirming facts quickly. They only become a problem when used for exploration, where they gather too little evidence.
How do I turn a closed question into an open one?
Change the opening word. Replace "Did," "Do," "Was," or "Is" with "How," "What," "Why," or "Tell me about" to invite a fuller answer.
What is the funnel technique?
It means starting with a broad open question to gather a rich answer, then narrowing with closed questions to confirm the specific details that matter.
Can an open question be too open?
Yes. A vague question like "Tell me about yourself" can cause rambling. Keep open questions focused, such as "Tell me about your most challenging project."
Which type should I use most?
Spend most of your time on open questions, since they gather the evidence you need, and use closed questions sparingly to confirm facts.
Conclusion
Open and closed questions are the two fundamental shapes of every interview question. Closed questions confirm facts quickly, while open questions unlock reasoning, detail, and genuine evidence. Because interviews exist to gather evidence, open questions should form the core of your questioning, with closed questions used to lock down specifics.
Master the simple art of choosing deliberately — leading with open questions, converting weak closed ones, and combining both through the funnel technique — and every question you ask will gather more, and better, evidence about the candidate in front of you.
Key Takeaways
Closed questions get facts; open questions get evidence. Lead with open questions starting with "How," "What," "Why," or "Tell me about," convert weak closed questions by changing the first word, and use the funnel technique — open to explore, closed to confirm.