article
The Cyclic Quadrilateral
This gives a short summary of the properties and theorems of cyclic quadrilaterals and links to some practical examples to be found elsewhere on the site.
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Complex Instruction - Raising Achievement Through Group-Worthy Tasks
Many NRICH tasks have been designed with group work in mind. Read about Jo Boaler's research on the benefits of collaborative work and watch a clip of a teacher working in this way.
problem
Ones Only
11 to 14
Find the smallest whole number which, when mutiplied by 7, gives a
product consisting entirely of ones.
problem
Number Juggle
7 to 11
Fill in the missing numbers so that adding each pair of corner
numbers gives you the number between them (in the box).
problem
Triangular Tantaliser
11 to 14
Draw all the possible distinct triangles on a 4 × 4 dotty grid. Convince me that you have all possible triangles.
problem
Logo Challenge 10 - Circles
11 to 16
In LOGO circles can be described in terms of polygons with an infinite (in this case large number) of sides - investigate this definition further.
problem
Triangles Within Triangles
14 to 16
Can you find a rule which connects consecutive triangular numbers?
problem
Favourite
Baravelle
7 to 16
What can you see? What do you notice? What questions can you ask?
article
Proof: A Brief Historical Survey
If you think that mathematical proof is really clearcut and universal then you should read this article.