Sampling – Year 9 maths lesson
Lesson 22 of 38 in the Year 9 maths course
UK version. UK school years, UK spelling and pounds (£). · US Math Department
A complete 45-minute lesson for Year 9 (ages 13–14) that runs on this page – at school or at home. Every answer is marked straight away, with a worked explanation.
- Time
- 45 minutes + 20 min homework
- Year
- Year 9 (ages 13–14)
- You need
- Paper, a pencil and this page
- Marked
- Instantly, with explanations
For parents: how to use this lesson
You don't need to know this topic yourself. The lesson explains each step on screen, one tidy step at a time. Every answer is marked straight away with a worked explanation, so you never have to mark anything.
- Read what your child will learn and the big ideas together.
- Press Start the lesson below and sit with your child for the teaching and the worked examples (about 19 minutes).
- Let them do the practice on their own. They choose Getting started, On track or Challenge – start on On track and move up after a few right in a row.
- Finish with the exit ticket and the talk question: “Why might asking people at a gym about exercise give a biased result?”
- Later that day or the next day: the homework (20 minutes), then a practice test.
Watch out for
- Using a sample of only friends or one class. Ask: does every member have an equal chance of being picked?
- Thinking a sample result is exactly right for the population. It is an estimate; bigger samples are usually better.
Tip for home: Talk about polls in the news: who was asked, and how many?
What your child will learn
We are learning to choose fair samples and use them to estimate facts about a population.
Success looks like
- I can explain population and sample.
- I can spot a biased sample.
- I can make an estimate from a sample.
Key words
- population
- the whole group being studied
- sample
- part of the population
- random
- every member has an equal chance
- bias
- a sample that is not fair
What to have ready
- Paper and a pencil
- This page on a computer, tablet or phone
- For the hands-on part: Pick a random sample of words from a book page and estimate the average word length.
The big ideas (for the adult)
A population is everyone or everything you want to know about; a sample is a smaller group you actually ask or measure.
A random sample gives everyone the same chance of being chosen, which helps avoid bias.
Use a sample to estimate: if 12 out of 40 in the sample like a song, about 30% of the population might.
The lesson, step by step
| Part | Time | How it is checked |
|---|---|---|
| Starter: quick recall | 5 min | Marked by Classfern |
| Teaching input | 10 min | Not assessed, self-checked |
| Worked examples and guided practice | 9 min | Not assessed, marked by Classfern |
| Independent practice | 15 min | Marked by Classfern |
| Plenary and exit ticket | 6 min | Marked by Classfern, self-checked |
Starter, "your turn", practice and exit ticket are marked by Classfern. Worked examples and teaching are not assessed. The hands-on task and the reflection are self-assessed. Explanations in talk are judged by the parent and not recorded.
The lesson
It runs here on the page. No sign-up and no names – progress is kept only in this browser.
Homework and practice at home
20 minutes: 10 practice questions, 3 multiple-choice questions and 2 to remember from earlier work, then a short reflection. New questions every time, all marked instantly.
More practice
More Year 9 maths lessons
- Prime factors, HCF and LCM
- Rounding and estimation
- Bounds and error intervals
- Standard form
- Laws of indices
- Powers and roots
- Units and measures
- Area of triangles, parallelograms and trapeziums
- Circles: circumference, area, arcs and sectors
- Volume and surface area
- Angle facts and parallel lines
- Angles in polygons
- Pythagoras' theorem
- Trigonometry: SOH CAH TOA
- Transformations
- Similarity and congruence
- Quadrilaterals and symmetry
- Coordinate geometry
- 3-D shapes, plans and elevations
- Quartiles, box plots and spread
- Pie charts and time series graphs
- Relative frequency and expected outcomes
- Venn diagrams and conditional probability
- Algebraic notation
- Substitution
- Simplifying expressions
- Expanding brackets
- Solving linear equations
- Inequalities
- Rearranging formulae
- Sequences and the nth term
- Straight-line graphs
- Graphs of functions
- Ratio
- Percentages
- Speed, density and pressure
- Scale drawings and maps
Curriculum
GCSE subject content S1: “infer properties of populations or distributions from a sample, whilst knowing the limitations of sampling”
GCSE subject content S5: “apply statistics to describe a population”
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Our lessons and questions are our own. They are not written or endorsed by any government department, testing agency or exam board.