classes:  lecturer. Teachers need flexibility, not rigid just sitting to read slides, there should be appropriate teaching ways for students to be more receptive.  curriculum. Teachers need flexibility, not rigid just sitting to read slides, there should be appropriate teaching ways for students to be more receptive.  facility. Teachers need flexibility, not rigid just sitting to read slides, there should be appropriate teaching ways for students to be more receptive.  general. Teachers need flexibility, not rigid just sitting to read slides, there should be appropriate teaching ways for students to be more receptive.