A presentation system capable of detecting one or more gestures and contacts on a touch sensitive display. The presentation system can displaying indicia of such contacts, such as when a user writes with a fingertip, and can remove or alter such indicia responsive to other gestures and contacts. The system can accurately distinguish between types of gestures detected, such as between a writing gesture and an erasing gesture, on both large and small touch sensitive displays, thereby obviating the need for a user to make additional selective inputs to transition from one type of gesture to another. The presentation system can distinguish between gestures appropriate for one type of writing and another. For example the system can determine that gestures correspond to writing in Chinese versus English, and display the writing in a style that is appropriate for that language.