By David Hearnshaw | GCSE Maths Tutor in Bawtry, Doncaster.
After 30 years of teaching GCSE Maths and examining for AQA, Edexcel, and OCR, I’ve seen the same mistakes appear on exam papers year after year. The good news? These mistakes are completely avoidable once students know what to look out for.
Here are the five most common GCSE Maths errors I see, and more importantly, how your child can avoid them.
Students arrive at the correct answer but don’t show how they got there. When they make a small calculation error, they lose all the marks instead of gaining method marks.
Students think showing working takes too much time, or they do calculations in their head to save space.
Always show your method. Even if you can do the calculation mentally, write down the steps. GCSE maths examiners award marks for correct methods, even if the final answer is wrong.
For example, if a question is worth 3 marks and you get the answer wrong but showed correct working, you might still earn 2 marks. Without working? Zero marks.
Examiner’s tip: I’ve marked thousands of papers. Trust me – showing your working is the easiest way to protect your marks.
Students answer a different question to the one asked. Classic examples:
Exam pressure makes students rush. They see familiar numbers or shapes and jump to the calculation without carefully reading what’s being asked.
Underline or highlight key words in the question:
Read the question twice – once before solving, once before moving on.
Check the units – if the question gives measurements in centimeters but asks for the answer in meters, you’ll need to convert.
Students don’t realize they have access to a formula sheet, or they forget to use it under exam pressure. They try to remember formulas and get them wrong.
Lack of familiarity with what’s on the formula sheet, or poor exam preparation.
Know what’s on your formula sheet BEFORE the exam.
The GCSE Maths formula sheet includes:
Practice using it during revision. Get comfortable finding formulas quickly. If you’re not sure of a formula in the exam, check the sheet first.
Don’t memorize what you don’t need to. Save your brain power for understanding concepts and methods instead.
Students spend too long on difficult questions and run out of time for easier marks at the end of the paper.
Determination to “crack” a hard question, or not knowing how to spot which questions are worth spending time on.
Know the marking: Roughly speaking, you have just over 1 minute per mark. A 4-mark question should take about 4-5 minutes.
If you’re stuck after 2 minutes, move on. Circle the question and come back to it if you have time at the end.
Do the questions you find easiest first. There’s no rule saying you must answer in order. Bank the marks you’re confident about, then tackle the harder ones.
Leave time to check your answers. Aim to finish with 5-10 minutes spare to review your work.
Students understand the method perfectly but make basic calculation mistakes: 6 × 7 = 48, or 15 – 8 = 6.
Over-reliance on calculators, exam stress, or rushing through calculations.
Check your arithmetic. If you calculated 6 × 7 = 48, do a quick sense check: “Is that roughly right? 6 × 7 should be around 40-something…” That catches the error.
Use your calculator properly. Make sure you know how to:
Practice mental arithmetic. Spend 5 minutes a day on times tables and basic calculations. Apps like “Times Tables Rock Stars” can help.
Read the question requirements. If it says “non-calculator,” don’t accidentally reach for your calculator. If it says “use your calculator,” make sure you do.
When you do practice papers or mock exams, don’t just check your score and move on. Analyze where you lost marks:
Understanding your patterns helps you avoid repeating the same mistakes in the real exam.
At Booster Tutors, we’ve spent 30 years helping students master GCSE Maths. As former examiners for AQA, Edexcel, and OCR, we know exactly what exam boards are looking for and where students typically lose marks.
Our face to face tutoring focuses on:
We’ve helped students improve from Grade 5 to Grade 8 in just one year. With the right support, remarkable progress is possible.
If your child is making these mistakes or struggling with GCSE Maths, we can help.
📞 Call David on 07800 646184 for a free consultation
Our tutoring center is in Bawtry, easily accessible from Doncaster and surrounding areas. Lessons start from just £19 per hour.
[Learn more about our GCSE Maths tutoring →]
About the Author: David Hearnshaw has 30 years of teaching experience and holds a degree in Physics and Astrophysics from the University of Sheffield. He has examined GCSE Maths papers for AQA, Edexcel, and OCR, giving him unique insight into what examiners look for.
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