From wikipedia
The traditional calendar consists of two pieces of card stock on top of each other. Twenty-four doors are cut out in the top layer, with a number ranging from one to twenty-four on each. Beginning on the first day of December, one door is opened each day, counting down the days remaining until Christmas Eve, from one to twenty-four where the 24th door often holds an extra surprise like an extra large piece of chocolate. Some modern calendars are labeled as "countdown calendars" and are designed to start at number 1 and count up to number 24 so the number of days until Christmas can be easily determined. Each compartment displays an image, which can be either a feature of the Nativity story and the birth of Jesus or a piece of paraphernalia to do with Christmas (e.g., bells or holly).
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types of advents
1. numbers only
3. illustration which ignores number placement - (ie numbers placed over picture whereever)
this is cute - each one reveals a penguin
4. illustration that incorporates number placement
5. Different ones altogether (other than felt stockings)
