Greenboards are commonly used in classrooms and lecture halls as a surface for teachers to write on. However, there are alternative options available that can serve the same purpose. One popular option is a whiteboard, which can be written on with dry erase markers and easily wiped clean. Another option is a blackboard, which can be written on with chalk and is often considered a classic classroom tool. More modern alternatives include interactive whiteboards and smartboards, which allow teachers to display and annotate digital content. Ultimately, the choice of surface depends on personal preference and the needs of each individual learning environment.