How a child's brain builds itself, from birth to about six, and how to tell a child who is simply on their own schedule from one who needs a closer look. The course starts with the brain under construction — neurons, synapses, pruning and myelin — and with plasticity: why early experience matters so much, and why the idea that a window slams shut forever at age three is a myth. It then walks through the milestones parents and teachers actually watch — motor, language, social-emotional and thinking skills — as ranges, not deadlines, using the CDC's 2022 checklists. It names the warning signs worth acting on, above all any loss of a skill a child already had, and explains how screening and evaluation work, who does them, and why an early evaluation costs little and waiting can cost a lot. It presents the neurodevelopmental conditions as DSM-5-TR describes them — autism, ADHD, intellectual disability, dyslexia and other learning disorders, developmental coordination disorder — with honest numbers, and it clears away the myths that still circulate: vaccines do not cause autism, sugar does not cause ADHD, bilingual homes do not cause language delay. It closes with what helps: early intervention, therapies ranked by evidence rather than by marketing, the family's role, inclusive school and the rights that protect the child. For parents, caregivers and educators. Educational content — it does not diagnose and does not replace a health professional.