Teacher guide — Grade 8, Unit 2: Asking good questions¶

Time: 3 lessons + project (about 5 periods). Track: A (no-code).

#	Lesson	Time
1	Statistical or not?	40–45 min
2	Surveys, measurements and bias	40–45 min
3	Fair samples	40–45 min
P	Unit project: Our survey plan	2 periods

Before you start¶

Materials: Strips of paper with sample questions; ruler and clock for a measurement trial.
Read docs/pedagogy/lesson-anatomy.md and docs/pedagogy/ai-use-policy.md.

If you have no computers / no internet¶

All eight units run on paper, calculators and the blackboard. Computers are optional (spreadsheet or CODAP, https://codap.concord.org); every activity below has a paper version.

Common misconceptions¶

"How tall am I?" is a statistical question. It has one answer; 'How tall are Grade 8 students?' expects variation.
More answers always means a better sample. A big biased sample is still biased.

Differentiation¶

Support: give a partially filled table / sentence starters; pair with a data-steward role.
Stretch: ask "what would change your conclusion?" and "who is missing?"

Answer key (check questions)¶

Lesson 1: Statistical or not? 1. Is 'What is the height of Mount Everest?' statistical?
Answer: No: one fixed answer. 2. Make 'How many siblings does Sita have?' statistical.
Answer: 'How many siblings do students in our class have?' 3. Why must a statistical question allow variation?
Answer: If every answer is the same there is nothing to analyse or compare.

Lesson 2: Surveys, measurements and bias 1. Rewrite 'Isn't maths the best subject?' neutrally.
Answer: 'Which subject do you like most?' (with options). 2. Name one way a sample can be biased.
Answer: e.g. asking only one section, only friends, only volunteers. 3. Give one thing better measured than asked.
Answer: e.g. height, travel time (use a clock).

Lesson 3: Fair samples 1. What is a population?
Answer: The whole group we want to learn about. 2. Why is drawing names from a box fair?
Answer: Everyone has an equal chance, reducing bias. 3. Can a large sample still be biased?
Answer: Yes, if the way we choose it favours some people.

Assessment¶

Starter quiz each lesson (3 questions, one recalling the previous lesson); unit quiz in quiz.yml; project marked with the rubric in docs/pedagogy/assessment.md; 2-minute oral check per group.

Alignment¶

Extends the Grade 8 compulsory Maths statistics chapter (pie chart, mean, median, mode) with question-forming, data collection and interpretation.

Answers: practice exercises¶

(a) yes (b) no: one value (c) yes (d) no: one time (it becomes statistical if asked over a whole year).
Population: everyone we want to learn about (all 600 students). Sample: the part we ask (30 students). Census: asking everyone in the population.
(a) "Should school be open on Saturdays? Yes / No / Not sure." (b) "How would you rate the new library? 1–5." (c) "What do you think are the main reasons students fail exams?" (open) — remove "lazy".
Two questions in one (double-barrelled). Split: "Do you have breakfast at school?" and "Do you have lunch at school?"
(a) measure: count beats for 30 s and double; (b) ask, with options; (c) measure with a scale; (d) ask, anonymously, rating 1–5 plus an open "why".
Compare: "Do students who walk take longer than students who come by bus?" Relate: "Do students who live further away (km) take longer?" or "Do students with longer journeys sleep less?"
Number students 001–600 (use the roll list), then draw 30 numbers from slips or a random-number table/app, skipping repeats. Every student has the same 30/600 = 5% chance.
Volunteer sample: listeners of that station only; people who care strongly reply; one person can SMS many times; people without phones/radio are missing.
Students near the door in this example all walk from far away; they share a feature linked to the answer. A convenience sample is biased when the reason people are "convenient" is linked to what we measure.
Peer check: look for leading words, missing options, two-in-one questions, social pressure.

Real-data exercises: notes¶

R1 Fixed-option examples: type of house wall/roof, toilet facility, fuel for cooking; open/fill-in: age, number of household members, mother tongue (coded). Social pressure: questions on disability, literacy, absent members, possessions. The census counts everyone because the government needs exact numbers for every ward (seats, budgets, services) and small areas are too small for samples.
R2 Describe: "What is the typical July rainfall?" Compare: "Is January colder in Jumla than in Biratnagar?" Relate: "Do hotter days have less rain?"
R3 Expect most samples of 6 within about ±8 minutes of 29.7; a few further. This previews sampling variation.