Data handling
Collecting, organising and showing data in bar graphs, pictographs and pie charts. Summarising data with the mode, median and mean. Read one part at a time and tap “I know this”. Then test yourself in the quiz.
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The data cycle
- Ask a question.
- Collect data (questionnaire, tally marks).
- Organise it in a table.
- Represent it in a graph.
- Read and discuss the results.
Graphs
- Bar graph: bars of equal width with gaps; read the height on the scale.
- Pictograph: pictures; the key says what one picture is worth.
- Pie chart: slices of a circle; the whole circle = 100%.
- Double bar graph: two bars side by side compare two groups.
Read the graph: find the top of the bar and read across to the scale. Banana = 9 and Pear = 3, so 9 − 3 = 6 more learners chose banana. Altogether: 6 + 9 + 3 + 5 = 23 learners.
Give every graph a title and label both axes.
Histograms
- A histogram looks like a bar graph, but the bars touch each other, because each bar is an interval of numbers (e.g. marks 0–9, 10–19, 20–29).
- Look for bias and errors: did you only ask your friends? Then the sample does not represent the whole school.
Summarising data
| Measure | How? | Data: 3, 5, 5, 7, 10 |
|---|---|---|
| mode | the value that occurs most often | 5 |
| median | the middle value after sorting | 5 |
| mean | total ÷ number of values | 30 ÷ 5 = 6 |
| range | largest − smallest | 10 − 3 = 7 |
Always sort from smallest to largest before finding the median. With an even number of values, the median is the mean of the two middle ones.
Remember this and test yourself
- Ask, collect, organise, represent, read.
- Mode = the most.
- Tally marks: four lines and the fifth across.
- Median = the middle after sorting.
- Bar graph: read the height on the scale.
- Mean = total ÷ count.
Write these points in your book. Read them again the night before the test.
Ask, Collect, Organise, Show, Discuss: the data cycle.
Important words
First say the answer yourself, then turn the card over.
Match column A to column B
Tap a word in column A, then its meaning in column B. You can also start in column B.
True or false?
Read the question and the answer. Is the answer right? Tap True or False.
Now the real quiz!
The quiz has many more questions on this topic. Every question shows straight away whether you are right and explains why.
Take the quiz: Data handling- Let your child work the examples on paper and explain them to you.
- The ticks (“I know this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 7 Mathematics. Always check your teacher’s notes and textbook too.