Concord Consortium
Leap Years and Calendars
How many birthdays do leap year babies have in a lifetime? Learners explore the question among others in a lesson focused on different calendar systems. Given explanations of the Julian, Gregorian, and Martian calendars, individuals use...
University of Cambridge
University of Cambridge: Nrich: Building Stars
This interactive activity gives you an opportunity to color in a tessellation that is different from the usual. Read the short introduction to find out more about this tessellation that doesn't repeat.