Our post office has evolved to include opportunities for mathematics as well as language. The children read names on mailboxes to deliver mail, and use the mailbox labels and word wall as references to help them write letters. With price tags and play money, they develop number sense as they role-play buying paper, postcards, and envelopes. Some ‘shopkeepers’ shared their emerging understandings of subtraction, making change for customers. We also began to explore measurement, weighing letters on a balance scale to determine the price of a stamp.