A method of enabling instruction of a computer to perform tasks, using an interface surface having command and object interactive elements, the interface surface having command and object interactive elements, the interface surface including coded data. The method includes having the computer system receive indicating data from a sensing device, which is generated when the sensing device is moved relative to the interface surface, the indicating data being indicative of a stroke designating the interactive elements. The computer system uses the indicating data to determine the interactive elements designated by the stroke before applying a command to at least one object using the designated interactive elements.