In the United States, 529 Plans are tax-advantaged investment accounts to save for educational expenses. Initially intended for higher education tuition, beginning in 2018, families can withdraw up to $10,000 tax-free per child for K–12 tuition. Unlike a Coverdell Education Savings Account (ESA), you can only use the money for tuition and not other educational expenses.
529 Plans vary by state. Consult a tax advisor in your state to learn more.