Or we could go with a real classic from Ye Olde Days: The Babylonian calendar[1]. A visual explanation is here [2]. I rather like that they use the physical pro

Or we could go with a real classic from Ye Olde Days: The Babylonian calendar[1]. A visual explanation is here [2]. I rather like that they use the physical properties of a pendulum to link length and time. 1: https://en.wikipedia.org/wiki/Babylonian_calendar https://en.wikipedia.org/wiki/Babylonian_calendar 2: https://upload.wikimedia.org/wikipedia/commons/7/71/Sumerian_Calendar_ISO_B0.svg https://upload.wikimedia.org/wikipedia/commons/7/71/Sumerian...