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Mathdoku demonstration
This video of Charlie and Liz solving a 6 by 6 Mathdoku may give you ideas for strategies to try.
Explaining, convincing and proving
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interactivityProof sorter - geometric sequence
Age16 to 18Challenge level
Can you correctly order the steps in the proof of the formula for the sum of the first n terms in a geometric sequence? -
interactivityProof sorter - the square root of 2 is irrational
Age16 to 18Challenge level
Try this interactivity to familiarise yourself with the proof that the square root of 2 is irrational. Sort the steps of the proof into the correct order. -
interactivityProof sorter - sum of an arithmetic sequence
Age16 to 18Challenge level
Put the steps of this proof in order to find the formula for the sum of an arithmetic sequence -
problemFixing it
Age16 to 18Challenge level
A and B are two fixed points on a circle and RS is a variable diamater. What is the locus of the intersection P of AR and BS? -
problemDoodles
Age14 to 16Challenge level
Draw a 'doodle' - a closed intersecting curve drawn without taking pencil from paper. What can you prove about the intersections? -
problemSummats clear
Age16 to 18Challenge level
Find the sum, f(n), of the first n terms of the sequence: 0, 1, 1, 2, 2, 3, 3........p, p, p +1, p + 1,..... Prove that f(a + b) - f(a - b) = ab. -
problemNatural sum
Age14 to 16Challenge level
The picture illustrates the sum 1 + 2 + 3 + 4 = (4 x 5)/2. Prove the general formula for the sum of the first n natural numbers and the formula for the sum of the cubes of the first n natural numbers.