To evaluate a historical source, judge its usefulness and reliability by examining its Nature, Origin and Purpose (NOP): what type of source it is, who made it and when, and why it was created. A source is rarely simply "true" or "false" — it is more or less useful for a particular enquiry.
What does evaluating a source actually mean?
Evaluating a source is not deciding whether you like it or whether it is biased. It means working out how useful it is for answering a specific historical question, and how much you can trust what it says. Every source is evidence of something, even a biased one — bias itself tells you about the author's viewpoint.
What is the NOP method for source evaluation?
NOP gives you three lenses to interrogate any source.
| Lens | Question to ask | Why it matters |
|---|---|---|
| Nature | What type of source is it? | A diary, poster and law each reveal different things |
| Origin | Who made it, where and when? | Closeness to the event affects reliability |
| Purpose | Why was it created? | Persuasion or propaganda shapes content |
How do you evaluate a source step by step?
Work through it in order so you do not miss anything:
- Read the provenance first — the caption telling you who, what, when and why.
- Identify the nature — primary or secondary, and what genre (letter, photograph, speech).
- Consider the origin — was the author present? Do they have first-hand knowledge?
- Question the purpose — were they trying to inform, persuade, or justify themselves?
- Weigh content against context — does it fit what you already know of the period?
Worked example: a wartime poster
Imagine a 1915 British recruitment poster urging men to enlist.
- Nature: A propaganda poster — designed to influence, not to record neutrally.
- Origin: Produced by the British government during the First World War.
- Purpose: To persuade men to join the army, so it exaggerates duty and downplays danger.
- Evaluation: It is unreliable as a record of soldiers' real experiences, but very useful as evidence of how the government tried to shape public opinion in 1915.
Notice how the same source is unreliable for one question and useful for another.
How do you write a good source evaluation?
Always tie your judgement to the enquiry question. Avoid the trap of dismissing a source just because it is "biased" — explain what the bias reveals and what the source is still useful for. A strong answer says "useful for X because... but limited for Y because...".
How do you compare two sources?
Many KS3 history tasks give you two sources and ask which is more useful, or whether they agree. Tackle this by evaluating each separately using NOP first, then comparing. Do the sources support or contradict each other? If they disagree, ask why — different authors, different purposes, or different moments in time can all explain it, and the disagreement itself is revealing. A source written by a participant and one written by a later historian are not simply "right" and "wrong"; they offer different kinds of evidence. When you write a comparison, avoid declaring one source the "winner" outright. Instead, explain what each contributes to the enquiry and why, weighing their nature, origin and purpose against the specific question you have been asked. This balanced approach is exactly what examiners reward.
Frequently asked questions
How do you evaluate the reliability of a historical source?
Examine its nature, origin and purpose. Consider whether the author was present at the event, when it was made, and why. A source written to persuade or justify is less reliable as a neutral record but can still be very useful evidence of attitudes at the time.
What is the difference between a primary and secondary source?
A primary source is from the time being studied — a letter, photograph or law. A secondary source is created later by someone interpreting events, such as a textbook or documentary. Both can be useful; primary sources give direct evidence, secondary sources offer analysis.
Does bias make a source useless?
No. A biased source is still useful evidence of the author's viewpoint and the period's attitudes. The skill is to recognise the bias, explain what causes it, and judge what the source can and cannot reliably tell you.
What does NOP stand for in history?
NOP stands for Nature, Origin and Purpose — the three things to examine when evaluating a source. Nature is the type of source, origin is who made it and when, and purpose is why it was created. Together they let you judge usefulness and reliability.
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