Angles, Polygons and Geometrical Proof: Age 11-14

This is part of our collection of favourite rich tasks arranged by topic.

If you are a teacher, you can find the whole collection on our Secondary Curriculum teacher page.
Alternatively, if you are a student, you'll find the same problems on our Secondary Curriculum student page.


  • Estimating angles
    game
    Favourite

    Estimating Angles

    Age
    7 to 14
    Challenge level
    1 out of 3

    How good are you at estimating angles?

  • Quadrilaterals game
    game
    Favourite

    Quadrilaterals Game

    Age
    11 to 14
    Challenge level
    1 out of 3

    A game for 2 or more people, based on the traditional card game Rummy.

  • Tilted Squares
    problem
    Favourite

    Tilted Squares

    Age
    11 to 14
    Challenge level
    1 out of 3

    It's easy to work out the areas of most squares that we meet, but what if they were tilted?

  • Triangles in circles
    problem
    Favourite

    Triangles in Circles

    Age
    11 to 14
    Challenge level
    1 out of 3

    Can you find triangles on a 9-point circle? Can you work out their angles?

  • Hidden Squares
    problem
    Favourite

    Hidden Squares

    Age
    11 to 14
    Challenge level
    1 out of 3

    Can you find the squares hidden on these coordinate grids?

  • Guess \my Quad
    problem
    Favourite

    Guess My Quad

    Age
    11 to 14
    Challenge level
    1 out of 3

    How many questions do you need to identify my quadrilateral?

  • Polygon Rings
    problem
    Favourite

    Polygon Rings

    Age
    11 to 14
    Challenge level
    1 out of 3

    Join pentagons together edge to edge. Will they form a ring?

  • Completing Quadrilaterals
    problem
    Favourite

    Completing Quadrilaterals

    Age
    11 to 14
    Challenge level
    1 out of 3

    We started drawing some quadrilaterals - can you complete them?

  • Polygon Pictures
    problem
    Favourite

    Polygon Pictures

    Age
    11 to 14
    Challenge level
    1 out of 3

    Can you work out how these polygon pictures were drawn, and use that to figure out their angles?

  • An Equilateral Triangular Problem
    problem
    Favourite

    An Equilateral Triangular Problem

    Age
    11 to 14
    Challenge level
    1 out of 3

    Take an equilateral triangle and cut it into smaller pieces. What can you do with them?

  • Square coordinates
    problem
    Favourite

    Square Coordinates

    Age
    11 to 14
    Challenge level
    2 out of 3

    A tilted square is a square with no horizontal sides. Can you devise a general instruction for the construction of a square when you are given just one of its sides?

  • Subtended angles
    problem
    Favourite

    Subtended Angles

    Age
    11 to 14
    Challenge level
    2 out of 3

    What is the relationship between the angle at the centre and the angles at the circumference, for angles which stand on the same arc? Can you prove it?

  • problem
    Favourite

    Right Angles

    Age
    11 to 14
    Challenge level
    2 out of 3

    Can you make a right-angled triangle on this peg-board by joining up three points round the edge?

  • Shapely pairs
    problem
    Favourite

    Shapely Pairs

    Age
    11 to 14
    Challenge level
    2 out of 3

    A game in which players take it in turns to turn up two cards. If they can draw a triangle which satisfies both properties they win the pair of cards. And a few challenging questions to follow...

  • Property chart
    problem
    Favourite

    Property Chart

    Age
    11 to 14
    Challenge level
    2 out of 3

    A game in which players take it in turns to try to draw quadrilaterals (or triangles) with particular properties. Is it possible to fill the game grid?

  • Opposite vertices
    problem
    Favourite

    Opposite Vertices

    Age
    11 to 14
    Challenge level
    2 out of 3

    Can you recreate squares and rhombuses if you are only given a side or a diagonal?

  • Quadrilaterals in a Square
    problem
    Favourite

    Quadrilaterals in a Square

    Age
    11 to 14
    Challenge level
    2 out of 3

    What's special about the area of quadrilaterals drawn in a square?

  • Star Polygons
    problem
    Favourite

    Star Polygons

    Age
    11 to 14
    Challenge level
    2 out of 3

    Draw some stars and measure the angles at their points. Can you find and prove a result about their sum?

  • Which solids can we make?
    problem
    Favourite

    Which Solids Can We Make?

    Age
    11 to 14
    Challenge level
    3 out of 3

    Interior angles can help us to work out which polygons will tessellate. Can we use similar ideas to predict which polygons combine to create semi-regular solids?

  • Square It
    problem
    Favourite

    Square It

    Age
    11 to 16
    Challenge level
    1 out of 3

    Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a square.

  • Semi-regular Tessellations
    problem
    Favourite

    Semi-Regular Tessellations

    Age
    11 to 16
    Challenge level
    1 out of 3

    Semi-regular tessellations combine two or more different regular polygons to fill the plane. Can you find all the semi-regular tessellations?

  • problem
    Favourite

    Cyclic Quadrilaterals

    Age
    11 to 16
    Challenge level
    1 out of 3

    Draw some quadrilaterals on a 9-point circle and work out the angles. Is there a theorem?

  • Parallelogram It
    problem
    Favourite

    Parallelogram It

    Age
    11 to 16
    Challenge level
    1 out of 3

    Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a parallelogram.

  • Pythagoras Proofs
    problem
    Favourite

    Pythagoras Proofs

    Age
    11 to 16
    Challenge level
    2 out of 3

    Can you make sense of these three proofs of Pythagoras' Theorem?

  • Rhombus It
    problem
    Favourite

    Rhombus It

    Age
    11 to 16
    Challenge level
    2 out of 3

    Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a rhombus.