Pupil Pref is designed to allow simple access to the page colour option that is in the Page Settings menu of Google Docs. The application provide 16 choices based around the work carried out by Prof Arnold Wilkins and his team at Essex University. Prof. Wilkins and his team are responsible for the "Intuitive Overlays" used by Optometrists. More can be found out about this work by searching for the book "Reading through Colour" The colours used in the add-on(s) are a "close" match and best approximation of the film overlays. With screens there are some limitations that prevent a full implementation being put in place. Certain constraints such as the brightness of the screen and the environmental lighting will also have a significant impact. It is therefore important to note that this add-on(s) for Google Apps has been created to assist those who might benefit from changing the colour of their background, by simplifying the process. With the add-on(s) installed it is possible to change the background of any document they have created or been provided (via Google Classroom for example).