Data Handling Notes, Quizzes & Revision
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Notes: Data Handling
Topic: topic_name_replace | Subject: subject_replace | For learners aged: age_replace (Kenyan context)
Learning outcomes
- Understand what data is and why we collect it (numbers, facts, observations).
- Collect and record simple data responsibly using tally marks and tables.
- Organise data into frequency tables and represent it with pictograms and bar graphs.
- Find and interpret simple measures: mode, median, mean (average) and range.
- Read charts and make simple conclusions about real-life Kenyan examples (e.g., rainfall, crop prices, exam scores).
Key vocabulary
Data โ pieces of information (numbers or words). Variable โ something that can change (e.g., rainfall, price). Tally โ quick marks for counting. Frequency table โ shows how often values occur. Pictogram โ pictures represent numbers. Bar graph โ bars show amounts. Mode โ most common value. Median โ middle value. Mean โ average. Range โ difference between highest and lowest.
Steps in Data Handling
- Ask a question (e.g., "How many households in our village grow maize?").
- Collect data carefully (surveys, lists, measurements). Use simple forms or tally charts.
- Record data in a table or tally chart.
- Organise into a frequency table.
- Represent with a pictogram or bar graph for easy reading.
- Interpret the data: find mode, median, mean and range; make conclusions and decisions.
Example (Kenyan context)
A teacher records the number of bananas sold by 8 traders at a local market in Kisumu on Monday:
| Trader | Bananas sold |
|---|---|
| A | 12 |
| B | 8 |
| C | 15 |
| D | 10 |
| E | 12 |
| F | 7 |
| G | 5 |
| H | 12 |
Frequency table (how many traders sold each number of bananas):
| Bananas | Frequency |
|---|---|
| 5 | 1 |
| 7 | 1 |
| 8 | 1 |
| 10 | 1 |
| 12 | 3 |
| 15 | 1 |
How to find Mode, Median, Mean and Range
Using the bananas data (sorted values): 5, 7, 8, 10, 12, 12, 12, 15
- Mode โ most common value: 12 (appears 3 times).
- Median โ middle value. Even number of items (8), so average of 4th and 5th: (10 + 12) / 2 = 11.
- Mean (average) โ sum รท count: (5+7+8+10+12+12+12+15)=81; 81 รท 8 = 10.125 โ 10.1 bananas.
- Range โ highest โ lowest: 15 โ 5 = 10 bananas.
Interpretation (Kenyan context): Mode = 12 means many traders sold 12 bananas; mean โ 10 suggests a typical number sold is around 10; range = 10 shows variation between small and large sellers.
Pictogram (simple)
Use one banana icon ๐ to represent 2 traders. Frequency: 12 (3 traders) โ 3 ร ๐ = ๐๐๐
7 โ ๐๐
8 โ ๐๐
10 โ ๐๐๐
12 โ ๐๐๐
15 โ ๐๐๐
Practical tips (for teachers and learners in Kenya)
- Collect local data: rainfall amounts for your county, maize prices in the nearest market, number of students walking to school each day.
- Use everyday items as counters (stones, beans) when making pictograms or tally charts.
- Label graphs clearly (title, axes, key) โ e.g., "Maize price in Kisumu Market, June".
- Discuss fairness: when using averages for planning (e.g., food distribution), check range and median, not only mean.
- Introduce simple digital tools if available (spreadsheet on a phone or school computer) to draw charts faster.
Practice questions
- A class of 10 pupils scored the following marks out of 20: 12, 15, 11, 14, 15, 10, 15, 8, 13, 14. Find the mode, median, mean and range.
- A farmer records rainfall (mm) for 7 days: 2, 0, 5, 8, 2, 2, 10. Draw a frequency table and a pictogram (use 1 drop icon = 2 mm).
- Why might the mean not be a good number to use if one trader sold 100 bananas and all others sold less than 20? (Hint: effect of outliers)
Answers (quick)
- Marks sorted: 8,10,11,12,13,14,14,15,15,15. Mode = 15, Median = (12+13)/2 = 12.5, Mean = (sum 127)/10 = 12.7, Range = 15 โ 8 = 7.
- Frequency: 0โ1, 2โ3, 5โ1, 8โ1, 10โ1. Pictogram with 1 drop = 2 mm: 0โโ, 2โโโโ, 5โโโโ (use half icon or note 5 โ 2+2+1). Explain scale choice to learners.
- An outlier (100) will pull the mean up, making it unrepresentative of most traders; median or mode show typical values better.
Summary
Data handling helps us collect, organise and use information to answer questions about our community (schools, markets, farms). In Kenyan classrooms, use local examples, simple tools (tally, table, pictogram, bar graph) and the measures mode, median, mean and range to describe data clearly and fairly.
Quick glossary
Tally: marks like |||| to count items quickly. Frequency: how many times a value occurs. Pictogram: pictures used as counts (key required).