One decision you made in your investigation
One piece of evidence you used
One uncertainty you are still sitting with
Ask the student to close or turn over their investigation. The vignette is conducted without reference to the work — that is what makes it diagnostic rather than rehearsed. It takes 90 seconds and does not require a private room or a formal setting. It can happen at the student's desk while others are completing final checks.
What was one decision you made in your investigation? What was one piece of evidence you used and why did you choose it? What is one thing you are still uncertain about? These three prompts are enough. Students who own their investigation will answer them without difficulty. Students who do not will reveal that immediately — and that is the teaching information the vignette is designed to produce.
The teacher notes the student's responses in three or four words per prompt. These notes form an authenticity record that sits alongside the submitted investigation. The notes are for the teacher's professional judgement, not for a compliance file. They answer the question: does what this student says match what this report implies they know?
Where the vignette and the investigation align, the student owns the thinking. Where they diverge, that gap is a teaching point — not a disciplinary matter. Return to the student with one question: can you show me where this decision appears in your investigation? That conversation develops the scientific thinking the task was designed to build.
A student investigating plant growth who says "I decided to control for soil type because I knew it would affect nutrient availability and I wanted to isolate the light variable" has demonstrated the variable control reasoning that the standard is designed to assess. The report may say the same thing — but the vignette confirms it belongs to the student.
The third prompt — one uncertainty you are still sitting with — is the one that most reliably separates a student who has thought scientifically from one who has produced a polished document. A student who says "I'm not confident my sample size was large enough to generalise, especially since three of my results were outliers" is demonstrating exactly the epistemic humility that good scientific practice requires. That sentence is also nearly impossible to produce without genuine engagement with the data.
For classes of 25 to 30 students, the vignette is most practical as a rolling check during the final session before submission — three to four students at a time while others are completing final edits. A teacher who runs vignettes with ten students per class before each internal assessment develops a reliable pattern of which students can account for their thinking and which need a different kind of support.
The Decision Vignette reveals whether the scientific thinking belongs to the student. It also happens to look a lot like what good scientific practice actually is — naming a decision, accounting for evidence, and holding uncertainty. A student who can do all three has engaged in the reasoning the investigation was designed to develop. A student who cannot is giving the teacher exactly the information needed to make a useful teaching move, not a disciplinary judgement.
The vignette notes function as a professional authenticity record for NCEA internal assessments. NZQA's authenticity expectations require teachers to be confident that submitted work represents the student's own understanding. The Decision Vignette is a structured, lightweight, and defensible way to develop that confidence — particularly for investigations where AI-assisted drafting cannot be detected by the report alone.