Do you know how to use a calendar? A calendar is a chart with numbers and words. It shows us the year, the months, the weeks, the days, and the dates. Can you find the date of a special day, like your birthday or a party?Do you know how to use a calendar? A calendar is a chart with numbers and words. It shows us the year, the months, the weeks, the days, and the dates. Can you find the date of a special day, like your birthday or a party?