Explaining, convincing and proving

  • Triangle in a Triangle
    problem
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    Triangle in a Triangle

    Age
    14 to 16
    Challenge level
    filled star filled star empty star

    Can you work out the fraction of the original triangle that is covered by the inner triangle?

  • Trapezium Four
    problem
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    Trapezium Four

    Age
    14 to 16
    Challenge level
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    The diagonals of a trapezium divide it into four parts. Can you create a trapezium where three of those parts are equal in area?

  • Nicely Similar
    problem
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    Nicely Similar

    Age
    14 to 16
    Challenge level
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    If the hypotenuse (base) length is 100cm and if an extra line splits the base into 36cm and 64cm parts, what were the side lengths for the original right-angled triangle?

  • Gutter
    problem
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    Gutter

    Age
    14 to 16
    Challenge level
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    Manufacturers need to minimise the amount of material used to make their product. What is the best cross-section for a gutter?

  • For richer for poorer
    problem
    Favourite

    For Richer for Poorer

    Age
    14 to 16
    Challenge level
    filled star filled star empty star

    Charlie has moved between countries and the average income of both has increased. How can this be so?

  • problem
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    Immersion

    Age
    14 to 16
    Challenge level
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    Various solids are lowered into a beaker of water. How does the water level rise in each case?

  • Folding Fractions
    problem

    Folding Fractions

    Age
    14 to 16
    Challenge level
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    What fractions can you divide the diagonal of a square into by simple folding?
  • Speeding boats
    problem
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    Speeding Boats

    Age
    14 to 16
    Challenge level
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    Two boats travel up and down a lake. Can you picture where they will cross if you know how fast each boat is travelling?

  • Partly Painted Cube
    problem
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    Partly Painted Cube

    Age
    14 to 16
    Challenge level
    filled star filled star empty star

    Jo made a cube from some smaller cubes, painted some of the faces of the large cube, and then took it apart again. 45 small cubes had no paint on them at all. How many small cubes did Jo use?

  • L-triominoes
    problem

    L-Triominoes

    Age
    14 to 16
    Challenge level
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    L triominoes can fit together to make larger versions of themselves. Is every size possible to make in this way?