Selective & OC practice. Turn mistakes into next steps.
Start with one tricky question. Understand the method, practise the skill and come back to it later. MistakeBook brings maths mistake review, selected Thinking Skills practice and writing foundations into one family learning space.
Free beta is open. Register and learn without an invitation code or payment card.
Worked example · Fractions
Question: What is 3/4 of 20? A child answers 5. Divide 20 by 4 to get one quarter (5), then multiply by 3 to get three quarters (15). Discuss whether the child stopped after the first step.
Try the skill
Try: What is 3/4 of 12? Answer: 9.
Apply the skill
Try: A box holds 24 apples. What is 5/8 of the box? Answer: 15 apples.
Discuss the idea
Review later: Explain why dividing by 4 alone only finds one quarter.
See it in 45 seconds · No registration
One question. A clearer next step.
Follow a maths mistake through explanation, focused practice and a parent learning record.
Illustrative animation · Example questions and data · No audio, with English and Chinese captions. Pause, seek or watch full screen.
Find your starting point
A little practice, with a clear purpose.
Maths practice
MistakeBook helps families review supported maths questions, including fractions, geometry and word problems. Upload a complete question to get an explanation and, when available, a short set of checked practice questions.
Explore practice & an example02Thinking Skills
MistakeBook currently offers checked practice for selected Thinking Skills areas: argument flaws, synonyms, and main idea and conclusion. Hidden assumptions have analysis and explanation only. Spatial rotation, folding and complex image matrices are not supported.
Explore practice & an example03Selective writing
Writing Studio offers six introductory lessons, draft writing or import, and AI learning feedback. It uses general writing methods in the context of public NSW Selective requirements. It does not provide official exam marks or predict placement outcomes.
Explore practice & an exampleFrom one question to a focused next step
Upload one complete question, review the explanation together, then practise the skill when checked exercises are available.
Discover the skill to practise
Identify the skill behind a question and discuss possible mistakes with your child. A skill label alone does not tell us why they answered incorrectly.
Practise the right concept
For supported skills, get practice that targets the same concept and passes our checks. Some questions may have fewer exercises or an explanation only.
See your learning evidence
See first-answer accuracy across different practice questions, skills to revisit and where more evidence is needed.
Parent-friendly learning insights
See what your child has practised and what to revisit.
MistakeBook groups saved questions and practice results by skill. Use these records to choose a next step and discuss learning with your child.
Explore Maths and Thinking Skills
View specific skills separately by subject, including skills identified in uploads that have not been practised yet.
Count new answers fairly
Each distinct practice question counts once towards first-answer accuracy. Repeat practice is recorded separately.
Build focused practice habits
Start with one question and a short practice set. Revisit skills over time; learning status is a practice indicator, not an exam prediction.
Skill progress
Example parent dashboard preview
Fraction of a quantity
First-answer accuracy: 67%
Sample representativeness
First-answer accuracy: 33%
These example results need more answers to different questions before showing a learning trend. An uploaded question alone is not evidence of mastery.
What you can use today
Maths
Analyse supported maths questions, review the answer and practise the same skill when exercises pass our checks.
Selected Thinking Skills
Argument flaws, synonyms and main ideas can have checked practice. Hidden assumptions currently have analysis and explanation only. Spatial puzzles are not supported yet.
Writing foundations
Write or import an essay, practise six foundational skills, and keep drafts and AI feedback. Activities use general writing methods in the context of public NSW Selective requirements. Examples are original, not examiner-rated model answers.
Questions with diagrams
For supported diagram questions, practice may use a self-contained text question testing the same skill. We do not promise a new diagram for every upload.
Practice availability depends on the question and our checks. AI can still make mistakes, so review the answer and explanation together.
Use MistakeBook alongside your exam preparation. It is not a complete exam course or a score prediction.
Questions parents ask
What is MistakeBook?
MistakeBook is an online learning tool for families preparing for NSW Selective and Opportunity Class exams. It combines maths mistake review, selected Thinking Skills practice, writing foundations and a private learning record.
Where should we start?
Try the public worked examples below, then create a parent account. Bring one complete maths or supported Thinking Skills question, or start a draft in Writing Studio. Review the explanation and choose one thing to practise.
Are uploaded questions added to a public question bank?
No. Family uploads are used for private learning analysis and practice tracking, not to create a public question bank. Upload only material you have permission to use. See our privacy and upload policies for details.
Does MistakeBook replace a complete exam course?
It is a focused practice companion. It does not cover every exam section or question type, and it does not predict scores or admission. AI can make mistakes; check explanations together and use the official NSW resources for exam information.