Viva questions come from the experiments the student performed, and they are far more predictable than students expect. They test whether the work in the file was actually done and understood — the principle behind an experiment, why a particular reagent was used, what a colour change indicated. A student who revisits their own file for an hour beforehand handles it comfortably.
| Format | Short oral questions, during or after the practical |
|---|---|
| Source | The experiments in the student’s own file |
| Tests | Whether the work was done and understood |
| Preparation | An hour with the file usually suffices |
What the questions are actually like
They are rarely obscure. Expect to be asked what the aim of an experiment was, why a particular indicator or reagent was chosen, what a colour change signified, what a precaution protects against, and what would happen if a step were done differently.
- "Why did you use this indicator rather than another?"
- "What does this colour change tell you?"
- "Why must the burette be rinsed with the solution rather than water?"
- "What would happen if you added excess reagent here?"
- "Why did this reading differ from the others?"
Every one of these is answerable by a student who performed the experiment attentively and wrote the entry themselves.
Why students struggle with it anyway
Because the file was copied, or because the experiments were performed mechanically without anyone explaining why each step existed. A student who followed instructions without understanding them has nothing to draw on when asked why.
The examiner is usually not trying to catch anyone out. The viva exists to check the file is genuine and the student understands their own work. Answering honestly — including saying a reading was anomalous and why you think so — lands better than a confident wrong answer.
How to prepare in an hour
- Go through the file experiment by experiment and, for each, be able to state the aim, the principle and the key observation in one sentence.
- For every reagent used, know what it was for.
- For every precaution written, know what it prevents.
- Be ready to explain any anomalous reading in your own results.
That is genuinely most of it. The preparation is short precisely because the questions are drawn from a bounded, known set of experiments.
The habit that makes it trivial
Understanding each experiment at the time it is performed. A tutor who spends ten minutes on the principle behind an experiment in the week it is done removes the need for viva preparation almost entirely — and improves the file at the same time.
Questions parents ask
How long is the viva?
Usually short, a few minutes per student. It is not an interrogation.
What if my child does not know an answer?
Saying so honestly and reasoning aloud generally scores better than guessing confidently. Examiners can tell the difference.
Can a home tutor prepare a student for the viva?
Easily, and it is one of the highest-return hours available. It needs the file and an hour.
Are questions asked outside the file?
Occasionally, on general lab safety or basic principles. Rarely far from the practical syllabus.