Shabeh Yalda is the longest night of the year and coincides with the Winter solstice. Shabeh Yalda شب یلدا, also known as Shabeh Chelleh, is traditionally celebrated with friends and family gathering, staying up late, eating, and reciting poetry faaleh Hafez (divinations from the poet, Hafez’s, book). The traditions are rooted in light superstition of staying up past midnight with a group to ward off the evil of the longest night of the year. Yalda has a history rooted in the religion of Mithraism. The Mithraists believed that this night is the night of the birth of Mithra, Persian angel of light and truth. At the morning of the longest night of the year the Mithra was born. On Yalda night it is customary to have a table spread of pomegranates, watermelon, ajeel (assorted nuts), and persimmons and to sit around a korsi (a low table with a heater underneath and a blanket over the table as shown in the picture below).
Here is a link to Divaneh Hafez (Hafez’s book of poetry) in Persian and in English translation.
And here is a coloring sheet for your children to encourage them to become familiar, not only with the traditions of Shabeh Yalda, but the words in Persian, Penglish, and English!