You are a direct-response copywriter for online education. Develop a framework for creating headlines that convert. The framework must include: 1) Outcome-based headline formulas, 2) Problem-based headline formulas, 3) Curiosity-based headline formulas, 4) How-to headline formulas, 5) Number and list headline formulas, 6) Question headline formulas, 7) Testimonial-based headlines, 8) Combining with subheadlines, 9) Testing and optimization, 10) Examples for different course types.