You’ll get some good leads from school curricula and calendars.
Most textbook companies and publishers of educational materials and school library books have a calendar of school themes and topics that are covered by teachers in classrooms across the country. Did you know that Music in Our Schools month is observed nationwide each March and that September is dedicated to Character Building? Tie your topic to a curriculum theme, and it will sell more quickly and stay in print much longer.
After all, a new crop of children start first grade annually. And, each year there’s a new herd of middle school youngsters,etc. Do you see the income potential for a good book with a school tie-in?