Cover lesson · IT · Year 10 · Intermediate
LNF: Numeracy → Learning that statistics represent data and that probability models chance helps us make informed inferences and decisions → Representing data
Name: Class: Date:
What this practises: drawing charts that show data honestly. An invented social media post uses a bar chart with an axis that starts at 3.3 hours, so a small rise looks huge. Pupils work out how misleading it is, redraw it with an axis from 0, then draw a pie chart of a second data set with a protractor. GCSE Digital Technology Unit 2 asks pupils to report on data with charts; this is practice only, not NEA work, and the data is invented.
Print: this sheet, one per pupil, and the stimulus sheet “Screen time explodes! A post and the data behind it”, one between two. Pupils need a pencil, ruler, protractor and calculator. No computers are needed.
Run: 5 min read the post and the data · 7 min Step 2, what is misleading? · 8 min Step 3, check the claim · 12 min Step 4, redraw the bar chart · 13 min Step 5, draw the pie chart · 5 min Step 6, a fair headline. Total 50 minutes.
Collect: this sheet. Checks you can make: Year 11 is really about 1.2 times Year 7, not 8 times; the pie chart angles are 126°, 108°, 72°, 36°, 18° and add up to 360°.
A local parents’ page has shared a chart claiming that Year 11 pupils spend eight times as long on screens as Year 7 pupils. The numbers in the chart are real survey results, but the way it is drawn is not fair. You will prove it, then draw the data properly.
Read the post and sections 2 and 3 of the stimulus sheet with your partner.
Give 3 things about the post or its chart that could mislead a reader.
(a) On the chart, the axis starts at 3.3. How tall does the Year 7 bar look (in hours above 3.3)? How tall does the Year 11 bar look? How many times taller does the Year 11 bar look?
(b) Use the real values, 3.4 and 4.1 hours. How many times bigger is Year 11 really? Give your answer to 1 decimal place.
(c) What is the real difference in minutes per day? What is the percentage increase from Year 7 to Year 11, to 1 decimal place?
Draw a bar chart of the mean hours per day for Years 7 to 11 on the grid. Your vertical axis must start at 0. Choose a scale so that the tallest bar uses most of the grid, and write your scale here: 1 square = ______ hours.
Your chart needs: a title, a label on each axis (with units), equal-width bars with equal gaps, and a scale with equal steps.
Look at your chart. Does it look like Year 11 spends eight times as long as Year 7?
(a) There are 120 pupils and 360° in a circle. How many degrees stand for 1 pupil? __________
(b) Complete the table.
| Main activity | Pupils | Working | Angle |
|---|---|---|---|
| Watching videos | 42 | ||
| Social media | 36 | ||
| Gaming | 24 | ||
| Messaging | 12 | ||
| Homework and learning | 6 | ||
| Total | 120 |
(c) Draw the pie chart. Start from the line already drawn and measure each angle from the end of the last sector. Label each sector or add a key, and give the chart a title.
(a) Why is a pie chart right for the Year 10 activities but wrong for the mean hours of each year group?
(b) Write a fair headline and a one-sentence caption for your bar chart, using at least one number.