Quadrilaterals and symmetry – Year 9 maths lesson
Lesson 17 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: “Is every square a rhombus? Is every rhombus a square?”
- Later that day or the next day: the homework (20 minutes), then a practice test.
Watch out for
- Thinking every quadrilateral with equal diagonals is a square. A rectangle has equal diagonals too: check the sides.
- Counting rotational symmetry of 0 for a shape with none. Every shape fits onto itself once: the lowest order is 1.
Tip for home: Find quadrilaterals in kites, road signs and windows.
What your child will learn
We are learning to use the properties of quadrilaterals, including their diagonals and symmetry.
Success looks like
- I can name quadrilaterals from their properties.
- I can use facts about diagonals.
- I can find lines and order of symmetry.
Key words
- rhombus
- four equal sides
- kite
- two pairs of equal adjacent sides
- diagonal
- a line joining opposite corners
- order of rotational symmetry
- how many times a shape fits onto itself in a turn
What to have ready
- Paper and a pencil
- This page on a computer, tablet or phone
- For the hands-on part: Cut out quadrilaterals, fold them to find lines of symmetry and turn them on a pin for rotational symmetry.
The big ideas (for the adult)
Quadrilaterals are sorted by their sides, angles, diagonals and symmetry: square, rectangle, rhombus, parallelogram, kite, trapezium.
The diagonals of a rhombus cross at right angles; the diagonals of a rectangle are equal; a kite has one line of symmetry.
Rotational symmetry: the order is how many times the shape fits onto itself in one full turn.
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
- Coordinate geometry
- 3-D shapes, plans and elevations
- Quartiles, box plots and spread
- Pie charts and time series graphs
- Sampling
- 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
National Curriculum for England, Year 9: “describe, sketch and draw using conventional terms and notations: points, lines, parallel lines, perpendicular lines, right angles, regular polygons, and other polygons that are reflectively and rotationally symmetric”
National Curriculum for England, Year 9: “derive and illustrate properties of triangles, quadrilaterals, circles, and other plane figures [for example, equal lengths and angles] using appropriate language and technologies”
Contains public sector information licensed under the Open Government Licence v3.0.
Our lessons and questions are our own. They are not written or endorsed by any government department, testing agency or exam board.