ScratchJr makes coding accessible to younger children (ages 5-7), enabling them to program their own interactive stories, games, and animations. To make ScratchJr developmentally appropriate for younger children, we revised the interface and provided new structures to help young children learn relevant math concepts and problem-solving strategies. ScratchJr is available as a free app for iPads, Android, and Chromebook. ScratchJr started as a collaboration between the MIT Media Lab, Tufts University, and Playful Invention Company, and it is now maintained by the Scratch Foundation. See scratchjr.org for more information.