A method performed by a data processing apparatus during an interactive session in which a user operating a user device at a first location is being instructed on how to accomplish a task by an assistant operating a production system at a second location remote from said first location, comprising: receiving, from the user device located at the first location, an image of the first location, the image depicting a layout of objects (103a-c) located at the first location and, for each object, an indicator element (104a-c) that identifies the object, wherein each indicator element includes a visual code (106a-c) that is unique to the indicator element such that each object is associated with a unique visual code, respectively; generating a user interface for the first location using the received image and the visual codes depicted in the image, wherein generating the user interface includes creating a user interface element (154a-c) corresponding to each visual code, wherein each user interface element includes a selectable icon (155a, 155c) for its corresponding visual code, the user interface depicting the layout of objects and the user interface element for each visual code, each user interface element being selectable to identify the object associated with the visual code; providing the user interface for display at a display of the production system located at the second location; receiving selection data specifying a selection made by the assistant of a particular user interface element displayed in the user interface at the production system located at the second location; and sending, from the production system located at the second location, command data to the user device located at the first location in response to receiving the selection data, the command data causing the user device located at the first location to activate an indicator (108a-c) which is configured to draw the user's attention to the object associated with the visual code corresponding to the selected user interface element; wherein each indicator element (104a-c) comprises a respective wireless communication device (112a-c) for each object (103a-c); and wherein activating said indicator (108a-c) comprises sending command data from the user device to the wireless communication device (112a-c) for the object associated with the visual code corresponding to the selected user interface element. receiving, from the user device located at the first location, an image of the first location, the image depicting a layout of objects (103a-c) located at the first location and, for each object, an indicator element (104a-c) that identifies the object, wherein each indicator element includes a visual code (106a-c) that is unique to the indicator element such that each object is associated with a unique visual code, respectively; generating a user interface for the first location using the received image and the visual codes depicted in the image, wherein generating the user interface includes creating a user interface element (154a-c) corresponding to each visual code, wherein each user interface element includes a selectable icon (155a, 155c) for its corresponding visual code, the user interface depicting the layout of objects and the user interface element for each visual code, each user interface element being selectable to identify the object associated with the visual code; providing the user interface for display at a display of the production system located at the second location; receiving selection data specifying a selection made by the assistant of a particular user interface element displayed in the user interface at the production system located at the second location; and sending, from the production system located at the second location, command data to the user device located at the first location in response to receiving the selection data, the command data causing the user device located at the first location to activate an indicator (108a-c) which is configured to draw the user's attention to the object associated with the visual code corresponding to the selected user interface element; wherein each indicator element (104a-c) comprises a respective wireless communication device (112a-c) for each object (103a-c); and wherein activating said indicator (108a-c) comprises sending command data from the user device to the wireless communication device (112a-c) for the object associated with the visual code corresponding to the selected user interface element.