📚 Student's Edition: Grade 2 Lesson 16-1 - Fractions | 学生版：二年级第16-1课 分数
Welcome to this IGCSE Mathematics revision lesson on fractions. This topic builds on the idea of equal parts and prepares you for ratios, percentages and algebraic fractions. Work through the examples carefully and test yourself with the practice focus at the end.
欢迎来到这节 IGCSE 数学分数复习课。本主题建立在等分概念之上，并为你学习比、百分数和代数分数做好准备。请仔细阅读示例，并在最后的考点聚焦中自我检测。
1. What Are Fractions? | 什么是分数？
A fraction is a number that represents a part of a whole. The bottom number, called the denominator, tells you how many equal parts the whole is divided into. The top number, called the numerator, tells you how many of those parts are being considered.
分数是表示整体一部分的数。底部的数称为分母，表示整体被等分成多少份；顶部的数称为分子，表示取了多少份。
For example, in the fraction ¾, the denominator 4 means the whole is split into 4 equal parts, and the numerator 3 means we take 3 of those parts. In IGCSE questions, you will often see fractions written as a numerator over a denominator, such as 5/6 or 7/10.
例如，在分数 ¾ 中，分母 4 表示整体被分成 4 等份，分子 3 表示取其中的 3 份。在 IGCSE 题目中，你经常会看到分子在上、分母在下的写法，例如 5/6 或 7/10。
2. Equal Parts and the Whole | 等分与整体
Fractions only work when the whole is divided into equal parts. If a pizza is cut into pieces of different sizes, you cannot describe each piece with a simple fraction of the whole pizza.
分数只有在整体被等分时才有意义。如果一个披萨被切成大小不同的块，你就无法用简单的分数来描述每一块占整个披萨的比例。
To identify the fraction of a shaded shape, first count the total number of equal parts. Then count the shaded parts. For example, a rectangle divided into 5 equal strips with 2 strips shaded represents ⅖.
要确定阴影图形的分数，首先数出总的等份数，再数阴影部分的数量。例如，一个长方形被分成 5 个相等的长条，其中 2 条被涂色，就表示 ⅖。
3. Halves, Thirds and Quarters | 一半、三分之一和四分之一
The most common fractions are halves, thirds and quarters. A half is written as ½ and means one out of two equal parts. Two halves make one whole, so the rule for adding halves is shown below.
最常见的分数是二分之一、三分之一和四分之一。二分之一写作 ½，表示两个等份中的一份。两个二分之一构成一个整体，因此两个二分之一相加的规则如下所示。
½ + ½ = 1
A third is written as ⅓, meaning one out of three equal parts, and a quarter is written as ¼, meaning one out of four equal parts. Three quarters, written ¾, is a non-unit fraction because it has a numerator greater than 1.
三分之一写作 ⅓，表示三个等份中的一份；四分之一写作 ¼，表示四个等份中的一份。四分之三写作 ¾，它是一个非单位分数，因为分子大于 1。
4. Unit Fractions | 单位分数
A unit fraction has 1 as the numerator. Examples include ½, ⅓, ¼, ⅕ and ⅙. Unit fractions are useful because any fraction can be built by adding unit fractions together.
单位分数的分子为 1。例子包括 ½、⅓、¼、⅕ 和 ⅙。单位分数很有用，因为任何分数都可以由单位分数相加得到。
For example, ¾ is the same as ¼ + ¼ + ¼. Recognising this helps you understand why a larger denominator means a smaller unit fraction: ⅙ is smaller than ¼ because the whole is split into more parts.
例如，¾ 等于 ¼ + ¼ + ¼。认识到这一点有助于你理解为什么分母越大，单位分数越小：⅙ 比 ¼ 小，因为整体被分成了更多的份数。
5. Non-Unit Fractions | 非单位分数
A non-unit fraction has a numerator greater than 1. Examples include ⅔, ¾ and ⅗. The numerator tells you how many copies of the unit fraction are being used.
非单位分数的分子大于 1。例子包括 ⅔、¾ 和 ⅗。分子告诉你使用了多少个单位分数。
For example, ⅗ means three copies of ⅕, so ⅗ = ⅕ + ⅕ + ⅕ on or an improper fraction as a mixed number, so keep the numerator and denominator clear.
例如，⅗ 表示三个 ⅕，所以 ⅗ = ⅕ + ⅕ + ⅕。在 IGCSE 考试中，你可能需要把带分数写成假分数，或把假分数写成带分数，因此要清楚分子和分母。
6. Fractions on a Number Line | 数轴上的分数
A number line helps you see the size of fractions. To place ⅓ on a number line from 0 to 1, divide the space between 0 and 1 into three equal jumps. Each jump is ⅓.
数轴可以帮助你观察分数的大小。要把 ⅓ 放在 0 到 1 的数轴上，将 0 和 1 之间的长度分成三等份，每跳一次就是 ⅓。
Fractions like ⅔ and ¾ can be compared by placing them on the same number line. The fraction further to the right is larger. This visual method is useful before learning to use a common denominator.
像 ⅔ 和 ¾ 这样的分数可以通过放在同一条数轴上来比较。位置越靠右的分数越大。在学习使用公分母之前，这种直观方法非常有用。
7. Comparing Simple Fractions | 比较简单分数
When two fractions have the same denominator, compare the numerators. For example, ⅗ is greater than ⅖ because 3 > 2.
当两个分数的分母相同时，比较分子即可。例如，⅗ 大于 ⅖，因为 3 > 2。
When the denominators are different, you can use fraction strips or find a common denominator. For example,
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