The Best Square

How would you judge a competition to draw a freehand square?

Trig-trig

Explore the properties of combinations of trig functions in this open investigation.

Chance of That

What's the chance of a pair of lists of numbers having sample correlation exactly equal to zero?

Factors and Multiples Graphs

Stage: 4 and 5 Challenge Level:
In this example, Steve chose the numbers $2, \dots, 10$ and was able to link the factor and multiple pairs without lines crossing.