Class 9 · Unit project
Unit 3 project: Same data, two headlines
Collect real numbers. Then write two headlines from them — one that misleads, one that's honest. If you can build the trick, you'll never fall for it.
The task
In Lesson 3.5, three true numbers misled a whole school. Today your group does it on purpose — and then undoes it.
You will collect real numbers, summarise them, and write two headlines from the same data: one that misleads, and one that tells the truth with its count and its limits. The misleading one proves you understand the trick. The honest one proves you can refuse it.
Work in groups of 3–4. One period. Everything in two-headlines.ods.
Collect (8 min)
Choose one and collect at least 20 values, with no names:
- Journey times to school, in minutes, from the class — with one extra column: walk / bus / other.
- Pencils, pens or books in each bag — with Class 9A / 9B.
- Daily temperature at 8 a.m. from the last month's weather record, with week 1–4.
- How many times a coin lands heads in 10 tosses, done 20 times, with who tossed as A, B, C.
Summarise (12 min)
- Mean, median, mode and range for the whole set.
- Split it by the extra column. Mean and median for each group.
- One probability, written three ways (fraction, decimal, percentage): the chance that a value picked at random is above the mean — or, for coins, of heads.
- One small-sample check: the mean of the first five values, against the mean of all of them.
Two headlines (12 min)
- Headline A — misleading. True numbers, misleading message. Use one trick from Lesson 3.5: one average for two groups · a percentage without its count · a small sample · an axis that doesn't start at 0. Make a chart that sells it.
- Headline B — honest. The same data. Include the count, the groups if they differ, and one limit. Make a chart that tells the truth.
- Under both, one line: which trick A used, and exactly how B undoes it.
Your own line (5 min, alone)
Each person writes three questions a reader should ask before believing Headline A — and which number in your sheet answers each one. Sign with your roll number. This part is marked for you alone.
Show it (3 min)
Show another group Headline A only. Can they spot the trick in thirty seconds?
How it is marked
Each row is marked 0–3. Rows 1–5 are shared by the group; row 6 is yours alone. Marks are returned privately and never compared with anyone else's.
Total: 18. Headline A must be built from true numbers. A false number scores 1 in row 4, because lying is not the skill.
1. The data
- 0Under 10 values or names in it
- 110–19 values
- 220+ anonymous values
- 320+ values, anonymous, with a column to split by
2. The summary
- 0Missing
- 1Some statistics, errors
- 2Mean, median, mode, range, all correct
- 3Correct, and says which one describes a typical value
3. The split and the probability
- 0Missing
- 1One of the two
- 2Both, correct
- 3Both, correct, and the small-sample check done
4. Headline A
- 0Missing
- 1Plainly false
- 2True numbers, misleading message
- 3True, misleading, and the trick named precisely
5. Headline B
- 0Missing
- 1Honest but vague
- 2Count, groups and a limit
- 3All three, and a chart that can't mislead
6. The reader's questions
Just you- 0Missing
- 1Questions, no numbers
- 2Three questions, answered from the sheet
- 3Three sharp questions, each tied to the exact number