Easy editing of work for better essays. Coursework pieces frequently need to be improved. It will obviously be simpler for the child who has a copy saved on computer than for one who has to rewrite a piece by hand. A copy can allows be saved on the computer just in case. This is especially useful where coursework is concerned.
Work does occasionally go missing in schools.
I have had students' coursework 'stolen' off my desk or cupboards broken into. Students also damage or steal each others work. Your child may also lose the work themselves but has a saved copy to revert to. Illustrations and charts can be pasted into pieces of work which add to the content and appearance. Word comes with its own ClipArt library of images.