Advent Calendar 2011 - Secondary Advent Calendar 2011 - a mathematical activity for each day during the run-up to Christmas. Age 11 to 18 Challenge level Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving Being curious Being resourceful Being resilient Being collaborative Problem Problem christmas! christmas! xmas! This Advent Calendar has a new activity to try with your friends for each day in December until Christmas Eve. Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Image Advent Calendar 2011 - a mathematical activity for each day during the run-up to Christmas.