The atom is science's biggest idea! And now it is known that even children from 4 years of age can grasp it, creating science education's biggest worldwide opportunity. Dr. Jenny Donovan and Dr. Carole Haeusler of the University of Southern Queensland conducted multiple studies to show that primary-age children, mostly aged 7-9 years in their particular studies, both understand and love learning about atoms. Currently formal teaching of atomic theory is delayed until secondary school, yet children are now learning it in over 30 primary schools across six countries, some from 4 years of age. This article shares resources to help primary teachers start simple when teaching atomic theory, building the concepts in small steps. Stages 1 and 2, enable teachers to teach atomic theory across the first two years. Stage 1 (lessons 1 to 7) can be taught to year 1 classes, and Stage 2 (lesson 8) to year 2 classes. The lessons included have guided animated videos to guide the children -- and teacher -- and are designed for easy delivery in a class by teachers without a science background.