📚 Year 7 OCR Maths: Mock Unit Test Walkthrough | Year 7 OCR 数学：单元测试模拟卷解析
A well-designed mock test is one of the most effective ways to prepare for a Year 7 OCR maths unit assessment. In this walkthrough, we break down a complete 10-question mock paper, covering key topics from Number, Algebra, Geometry and Statistics. Each question is explained step by step, with worked solutions, common pitfalls and smart revision strategies. Follow along to boost your confidence and master the skills examiners look for.
一套精心设计的模拟测试是为 Year 7 OCR 数学单元评估做准备的最有效方式之一。在这篇解析中，我们将拆解一份完整的 10 题模拟卷，涵盖数、代数、几何与统计的核心知识点。每一题都提供逐步讲解、完整解题过程、常见错误以及高效的复习策略。跟随解析提升你的信心，掌握考官关注的关键技能。
1. Overview of the Mock Unit Test | 模拟单元测试概述
This mock paper contains ten questions that mirror the style and difficulty of a typical OCR Year 7 unit test. The test covers four main strands: Number (including fractions, decimals, percentages and order of operations), Algebra (simplifying expressions and solving equations), Geometry (angles and area), and Statistics (interpreting bar charts). The total marks are 30, and you should aim to complete the paper in 35–40 minutes.
这套模拟卷包含 10 道题目，真实再现了 OCR Year 7 单元测试的题型和难度。试卷覆盖四大主线：数（含分数、小数、百分数和运算顺序）、代数（化简表达式与解方程）、几何（角度与面积）以及统计（解读条形图）。总分为 30 分，建议用时 35–40 分钟完成。
Each question starts with a clear stem and often includes a problem-solving twist. Marks are awarded for method as well as the final answer, so you should always show your working out. The mark scheme values careful step-by-step logic, accurate use of mathematical symbols and simplified answers where appropriate.
每道题都从一个清晰的设问开始，并且经常包含一些灵活运用的小挑战。评分不但看最终答案，也看解题过程，因此你必须展示演算步骤。评分标准重视有条理的逐步推导、数学符号的正确使用，以及必要时将答案化为最简形式。
Topics have been selected to align with the OCR curriculum framework for Year 7, focusing on foundational skills that will be built upon in later years. Understanding these building blocks is essential for success in more advanced topics like ratio, probability and compound geometry.
选题严格对应 OCR Year 7 课程框架，着重于今后学习必不可少的基础技能。掌握这些知识模块对于学好比例、概率和复合几何等进阶内容至关重要。
2. BIDMAS and Order of Operations | BIDMAS 与运算顺序
Question: Evaluate 15 + (6 × 2 − 4) ÷ 2.
题目：计算 15 + (6 × 2 − 4) ÷ 2。
The key rule is BIDMAS (or BODMAS), which stands for Brackets, Indices, Division and Multiplication, Addition and Subtraction. Always work from left to right for operations of the same priority. Here, the brackets contain both multiplication and subtraction, so handle the multiplication inside first.
核心规则是 BIDMAS（或 BODMAS），即括号、指数、除法与乘法、加法与减法。同级运算从左到右依次计算。本题中括号内含有乘法和减法，因此优先处理括号内的乘法。
12. Then perform the subtraction: 12 − 4 = 8. The expression now simplifies to 15 + 8 ÷ 2.
括号内计算：先算 6 × 2，得 12。然后做减法：12 − 4 = 8。此时表达式简化为 15 + 8 ÷ 2。
precedence over addition. 8 ÷ 2 = 4, so we have 15 + 4. Finally, add to get the answer 19.
接下来，除法优先于加法。8 ÷ 2 = 4，于是式子变为 15 + 4。最后做加法，得出答案 19。
Common mistake: some students add 15 and 8 first to get 23, then divide by 2 and obtain 11.5. That ignores the priority of division and the effect of the brackets. Always apply BIDMAS carefully to avoid losing marks.
常见错误：有些学生先将 15 和 8 相加得 23，再除以 2 得到 11.5。这忽视了除法的优先级以及括号的作用。务必小心应用 BIDMAS 避免失分。
3. Converting Decimals to Fractions | 小数化成分数
Question: Write 0.36 as a fraction in its simplest form.
题目：将 0.36 写成一个最简分数。
The decimal 0.36 means 36 hundredths, so we start by writing it as 36/100. The next step is to simplify by finding the highest common factor (HCF) of 36 and 100. Both numbers are divisible by 4, and 4 is the largest factor they share.
小数 0.36 表示 36 个百分之一，因此可以先写成分数 36/100。下一步是找出分子分母的最大公因数（HCF）来进行化简。36 和 100 都能被 4 整除，且 4 正是它们的最大公因数。
ied fraction is 9/25. Since 9 and 25 have no common factors other than 1, this is the simplest form.
分子分母同除以 4：36 ÷ 4 = 9，100 ÷ 4 = 25。化简后的分数为 9/25。因为 9 和 25 除 1 以外没有其他公因数，所以这就是最简分数。
To check your answer, convert 9/25 back to a decimal by dividing 9 by 25. You should get 0.36. This reverse check reassures you that the fraction is equivalent and the simplification is correct.
为了检查答案，你可以把 9/25 重新转化为小数：9 ÷ 25 = 0.36。这个反向验算能确保分数等价且化简正确。
Quick tip: recognising common fraction-decimal equivalents like 0.25 = 1/4, 0.5 = 1/2 and
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