Mathematical problem posing (MPP) is one construct with many manifestations. It can refer to different activities and is represented by tasks. No matter what it represents, it is related to problem solving and can be done individually or in groups. MPP has psychological and social values. MPP is a means and a goal; a product and a process, structured or open, being researched as a variable (dependent or independent variable) and used in practice. In this book, three of the variables in research on MPP were task, subject, and situations. Three target subjects (participants) were students, teachers, and parents. Under the waves of Taiwan curriculum change, a researcher went to practice MPP. She documented cases with content-specific examples in topics from different strands, at varying grade levels, and/or for participants from different backgrounds under various conditions of partnerships with a conscientious teacher educator. The cases showed possibilities and difficulties. In all, using MPP in learning/teaching/parenting is challenging but feasible.