This lesson introduces modals used to express permission, obligation, and prohibition. It defines modals as auxiliary verbs that provide additional information about the function of the main verb. The lesson explains that modals cannot change form and are often placed before the base form of the main verb. It then covers the specific modals used to express each category: can, could, may, might for permission; can't, mustn't for prohibition; and has/have to, must for obligation. Students are assigned to create a original dialogue using these modals and record a creative video presentation of it.