Overview: In today's episode, Maddie is sending a letter in the post to the CBeebies house. She finds out how posting a letter works as she follows the letter's journey from the post box to the sorting office and finally to the house. Using a special infrared light, Maddie shows us how stamps are scanned to tell if they are first or second class. Next, she visits a factory where colouring pencils are made. She finds out how the coloured crayon inside is made from clay and, using her slow-motion camera, we see the wooden shaft of the pencil being made.