Working Systematically at Stage 4 and 5
How Old Am I?
Age 14 to 16
Challenge Level 
In this problem students create quadratic equations and solve them by factorisation or by using the quadratic formula. The follow-up questions offer the chance for some interesting generalisations and justifications.
Odds and Evens Made Fair
Age 14 to 16
Challenge Level
To search for a fair game in this probability task, students will need to work systematically and record their findings appropriately.
Sorted
Age 14 to 18
Challenge Level
This problem uses playing cards and video to introduce students to some well-known sorting algorithms.
A Long Time at the Till
Age 14 to 18
Challenge Level
This problem provides an introduction to advanced mathematical behaviour which might not typically be encountered until university. The content level is secondary, but the thinking is sophisticated and will benefit the mathematical development of school-aged mathematicians.