IGCSE past paper solutions, explained mark by mark.
Mark schemes tell you what earns the marks, not why. Give the explainer a past paper question and it finds the mark scheme, then walks you through every point in plain words, ending with the answer you should write. AS and A Level papers too.
Typed, photo or PDF · past papers 2015 to June 2026
3 (b) Explain why the resistance of a thermistor decreases as its temperature rises. [2]
so current increases for same p.d. B1
- First mark: heating gives more electrons enough energy to break free, so there are more charge carriers to move.
- Second mark: more carriers means more current for the same p.d., and since R = V ÷ I, the resistance falls.
How it works
One question in. Every mark explained.
- 1
Give it the question
Type it, paste a screenshot or photo, or pick it straight out of the question paper's PDF. Include the mark allocation.
- 2
We find the mark scheme
Leave the mark scheme empty and we look the question up in the past papers, then show you which paper and question we found.
- 3
See where every mark comes from
Each point in the scheme, explained in plain words: what it wants, and why it gets the mark.
More than the answer.
Copying a mark scheme gets you one question. Understanding why each point earns its mark gets you the next one too.
The why, not just the what
Why the mark scheme says what it says, step by step, in simple words.
Formulae and concepts
Each formula and idea a step relies on, explained where it's used.
How to tackle it next time
How to approach questions like this one, with a simple example if it helps.
The answer to write
It ends with the answer you should give, built from the mark scheme's points.
One-tap follow-ups
Simpler, Full-mark answer, Common mistakes, Similar question: or type your own question about it.
Diagrams and graphs too
Send a question or scheme as an image when it's a diagram the text can't capture.
Got the PDFs?
Open the paper beside it.
Open the question paper and mark scheme together, side by side on a big screen or one at a time on your phone, and work through them question by question.
Select, don't retype
Highlight a question in the paper and use it as the question, or add text from the mark scheme.
Send a whole page
For a diagram or graph, send the page as an image instead.
The right scheme, faster
With a paper open under its Cambridge file name, such as 0625_s23_qp_42.pdf, we look only in that paper.
Your files stay with you
The PDFs open on your device. Only the question and scheme you choose are sent to be explained.
Never taken on trust
When we find a mark scheme, we say which paper and question it's from. If we're not sure, it's labelled as our best guess so you can check it's the same question, and if it isn't, one tap clears it. When we can't find a scheme at all, you get a model answer and we tell you that's what it is. The explanation itself is written by AI, so it can still slip up: if it doesn't make sense, ask again or check with your teacher.
For the best explanations
- Give the whole question part, with its mark allocation.
- Include the question's words, even with a photo, so we can find the scheme.
- Explain one part at a time, like 3(b), not the whole of question 3.
- Check the paper we found matches yours.
Done the whole paper?
The explainer is for one question at a time. To have a paper you've answered marked against the official scheme, with every lost mark explained on your own script, use the paper checker.
More about the paper checkerPaper explainer questions
How does the past paper explainer work?
You give it a question from a Cambridge past paper: typed, as a photo or screenshot, or selected from the paper's PDF. If you don't add the mark scheme, CIE Buddy looks the question up and fetches that question's part of the scheme. Then it explains each marking point in plain words, and finishes with the answer you should write.
Do I need to have the mark scheme?
No. Leave it empty and we search the past papers for the subjects on your profile, or just the paper you've opened, using the question's wording. We show which paper and question it came from, so you can check it's the right one, or paste in a scheme of your own.
What if it can't find the mark scheme?
You get a model answer instead. That answer isn't checked against an official scheme, so treat it as a guide and compare it with the real scheme when you can.
Can I use a photo of the question?
Yes, for both the question and the mark scheme. To look the mark scheme up for you, though, it needs the question's words, so type or select at least part of the question text as well.
Which past papers does it cover?
It can find mark schemes in a bank of papers from 2015 to June 2026, for over 100 IGCSE syllabuses and nearly 80 AS & A Level ones. You can also paste in any mark scheme yourself and have it explained.
Are the explanations always right?
They follow the mark scheme you give it, but the explanation is written by AI and can still be wrong or unclear in places. If something doesn't add up, ask it to explain again, check with your teacher, and give the answer a thumbs down so we can look at it.
What's the difference between this and the paper checker?
The explainer takes one question and shows you how its marks are earned. The paper checker takes a whole paper you've answered, marks it against the official scheme, and explains the marks you lost.
Stuck on a mark scheme? Let's go through it.
Make an account with your email or Google, add your subjects, and give it the question that didn't make sense.
Explain a question