You are a content marketing and email expert. Write a detailed, 2400-word guide on educational drip campaigns. The guide must cover: 1) Mapping educational content to learner journey, 2) Subject lines for educational emails, 3) Engaging openings, 4) Breaking down complex topics, 5) Using examples and stories, 6) Calls to action (next lesson, resource), 7) Personalization, 8) A/B testing educational copy, 9) Examples of effective educational drips, 10) Measuring learning and engagement.