📚 Year 7 OCR Statistics: Summer Preparation and Bridging Course | 七年级OCR统计：暑期预习与衔接课程
Statistics is the science of collecting, organising, analysing, and interpreting data to help us make informed decisions. In Year 7, you will build foundational skills: gathering data, drawing graphs, calculating averages, and beginning to explore probability. This summer bridging guide is designed to give you a confident start by breaking down each topic into simple, bilingual explanations and useful examples. Whether you are moving up from primary or starting a new school, working through these sections will make your first statistics lessons feel familiar and manageable.
统计学是一门收集、整理、分析和解读数据以帮助做出明智决策的科学。在七年级，你将打下扎实基础：收集数据、绘制图表、计算平均数，并初步探索概率。这份暑期衔接指南通过简单易懂的双语解释和实用例子，帮你自信开学。无论你是从小学升上来还是进入新学校，逐节学习这些内容都能让你在第一节统计课上倍感轻松。
1. What is Statistics? | 什么是统计学？
Statistics is everywhere – in weather forecasts, sports scores, medical trials, and even video game rankings. It helps us understand patterns in the world by turning raw numbers into meaningful information. In Year 7 OCR Statistics, you will learn to handle data safely, ask sensible questions, and present your findings clearly. The subject is split into descriptive statistics (summarising data) and a gentle introduction to probability (measuring chance).
统计学无处不在——天气预报、体育比分、医学试验，甚至电子游戏排名都离不开它。它通过把原始数字转化为有意义的信息，帮助我们理解世界中的规律。在七年级OCR统计课程中，你将学习安全处理数据、提出合理问题，并清晰展示你的发现。这个学科分为描述统计（总结数据）和概率的初步介绍（度量机会大小）。
2. Collecting Data: Types and Methods | 收集数据：类型与方法
Data can be collected in two main ways: primary data is gathered by you directly through surveys, counting, or measurements; secondary data comes from existing sources like websites, books, or databases. We also classify data as categorical (e.g. favourite colour, pet type) or numerical (e.g. height, number of siblings). Understanding the difference is key because it determines which graphs and calculations to use later.
数据收集主要分两种：一手数据是自己直接通过调查、计数或测量收集的；二手数据来自现有来源，如网站、书籍或数据库。我们还会把数据分为分类数据（例如最喜欢的颜色、宠物类型）和数值数据（例如身高、兄弟姐妹数量）。理解这些区别很关键，因为这决定了后续使用哪种图表和计算方式。
3. Organising Data: Tally Charts and Frequency Tables | 整理数据：计数表与频数表
Once data is collected, it needs to be organised. A tally chart uses marks (IIII and a diagonal stroke for five) to count occurrences quickly. You then transfer the counts into a frequency table, which shows each category and how many times it appears. For example, if 12 classmates like cats and 8 like dogs, the frequency table lists ‘Cats’ with a frequency of 12, ‘Dogs’ with 8. This is your first step in data analysis.
收集到数据后需要整理。计数表用记号（画竖线，每五条用斜线穿过）来快速记录发生次数。然后把计数转化为频数表，显示每个类别及其出现次数。比如，12个同学喜欢猫，8个喜欢狗，频数表会列出“猫”频数12，“狗”频数8。这是数据分析的第一步。
4. Pictograms and Bar Charts | 象形图与条形图
A pictogram uses simple pictures or symbols to represent data, where each symbol stands for a certain number of items (e.g. one book icon = 5 books read). You must always include a key. A bar chart displays categorical data with rectangular bars; the height of each bar shows the frequency. Remember, the bars should be of equal width and not touching each other. These visual tools make comparisons easy.
象形图用简单图画或符号表示数据，每个符号代表一定数量的项目（例如一个书本图标代表读了5本书）。必须附上图例。条形图用长方形条展示分类数据，每个条的高度表示频数。记住，条宽应相等，且条与条之间不接触。这些可视化工具让比较一目了然。
5. Line Graphs and Time Series | 折线图与时间序列
When data is collected over time, like daily temperatures or weekly savings, a line graph is the best choice. Plot points for each time period, then connect them with straight lines. This shows trends – whether values are rising, falling, or staying steady. Line graphs can also be used to compare two sets of data by drawing several lines on the same axes, as long as you label clearly.
当数据按时间收集时，比如每日温度或每周存款，最适合使用折线图。为每个时间段描点，然后用直线连接。这样能看出趋势——数值是在上升、下降还是保持稳定。折线图也可以在同一坐标轴上绘制多条线来比较两组数据，但必须标注清楚。
6. Mean, Median, Mode, and Range | 平均数、中位数、众数和极差
These are the four common ways to summarise a data set. The mode is the most frequent value. The median is the middle value when numbers are in order. The mean is the sum of all values divided by the count (often called the average). The range is the difference between the largest and smallest values, telling us how spread out the data is. For example, in the set 2, 3, 3, 5, 7: mode = 3, median = 3, mean = (2+3+3+5+7) ÷ 5 = 4, range = 7 − 2 = 5.
这四种方法常用来总结数据集。众数是出现次数最多的值。中位数是把数字按顺序排列后中间的那个值。平均数是所有值的总和除以个数（通常就叫平均数）。极差是最大值与最小值之差，告诉我们数据的分散程度。例如，在数据集{2, 3, 3, 5, 7}中：众数 = 3，中位数 = 3，平均数 = (2+3+3+5+7) ÷ 5 = 4，极差 = 7 − 2 = 5。
7. Interpreting Pie Charts | 解读饼图
A pie chart is a circle divided into sectors, where each sector’s angle represents the proportion of a category. The whole circle (360°) equals the total data. To find the angle for a category, use: angle = (category frequency ÷ total frequency) × 360°. When interpreting, you can compare the sizes of slices or calculate actual frequencies if you know the total. Always check that the percentages or angles add up to 100% or 360°.
饼图是一个被划分成扇形的圆，每个扇形的角度代表一个类别的比例。整个圆（360°）对应全部数据。计算某个类别的角度公式为：角度 = (该类频数 ÷ 总频数) × 360°。在解读时，你可以比较扇形的大小，或者如果知道总数，可以反推实际频数。一定要检查百分数或角度加起来是否为100%或360°。
8. Probability: The Basics | 概率基础
Probability measures how likely an event is to happen. It is a number between 0 and 1, where 0 means impossible and 1 means certain. You can describe probability in words: impossible, unlikely, even chance, likely, certain. For example, the probability of flipping a fair coin and getting heads is about ½, or an even chance. This language is the first step before calculating with fractions.
概率用来衡量事件发生的可能性大小。它是一个介于0和1之间的数字，0表示不可能，1表示必然发生。你可以用文字描述概率：不可能、不太可能、一半可能、很可能、一定。例如，抛一枚均匀硬币得到正面的概率大约是½，即一半可能。这种语言表达是使用分数计算之前的首要步骤。
9. Probability Scales and Simple Fractions | 概率标度与简单分数
We place probabilities on a scale from 0 to 1. A probability scale helps to visualise the chance. You will learn to write probabilities as fractions: Probability = (number of favourable outcomes) ÷ (total number of possible outcomes). A fair six-sided die showing a 3 has probability 1/6. Rolling an even number (2,4,6) is 3/6 = 1/2. Always simplify fractions when you can.
我们把概率标记在0到1的标度上，这有助于直观理解机会大小。你将学习用分数表示概率：概率 = (有利结果的数量) ÷ (所有可能结果的总数)。掷一个均匀六面骰子得到3的概率是1/6。掷出偶数（2、4、6）的概率是3/6 = 1/2。记得尽量约简分数。
10. Experiments and Predictions | 实验与预测
Probability can be tested by performing experiments. For instance, if you toss a coin 50 times, you might not get exactly 25 heads – that’s expected relative frequency, but real results vary. The more trials you do, the closer the experimental probability usually gets to the theoretical probability. You can then use probability to predict outcomes: if the chance of rain is 0.2, you can predict it will rain on about 2 out of 10 similar days.
通过做实验可以检验概率。比如，你抛硬币50次，可能不会恰好得到25次正面——那是期望的相对频率，但实际结果会有波动。实验次数越多，实验概率通常越接近理论概率。你还可以用概率进行预测：如果下雨的概率是0.2，你可以预测在类似的10天中大约有2天会下雨。
11. Working with Large Data Sets | 处理大型数据集
In real life, data can be hundreds of rows long. You might use grouped frequency tables to manage numeric data, where values are placed into intervals like 0–9, 10–19, etc. Mean can be estimated from grouped data using the midpoint of each interval. Spreadsheets are useful tools – they can sort, filter, and graph data quickly. Learning basic spreadsheet skills will give you an advantage in handling larger investigations.
在现实生活中，数据可能长达数百行。你可以使用分组频数表来管理数值数据，把数值放入区间，如0–9、10–19等。分组数据的平均数可以利用各区间的中点来估算。电子表格是很有用的工具——它能快速排序、筛选和绘图。掌握基本的电子表格技能会让你在处理大型调查时更具优势。
12. Revision and Summer Practice Tips | 复习与暑期练习建议
During the summer, keep statistics fun. Try small surveys with family – favourite fruits, screen time, or daily step counts. Draw charts from real data you find in online weather reports or sports statistics. Make a probability game using dice or spinners. Create a mini-project: collect, organise, and present data on a topic you enjoy, then calculate averages and talk about your findings in both English and Chinese. This active revision will cement your Year 7 skills long before the term starts.
暑假期间，让统计变得有趣。试着和家人做小型调查——最喜欢的水果、屏幕时间或每日步数。用网上天气报告或体育统计数据绘制真实的图表。制作一个骰子或转盘的概率游戏。开展一个小项目：选择一个你喜欢的话题，收集、整理并展示数据，然后计算平均数，并用英中双语聊聊你的发现。这种主动复习能在学期开始前牢固掌握七年级的关键技能。
Published by TutorHao | Statistics Revision Series | aleveler.com
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