Informal Reports : Many of the comments that we have made about other forms of written communications apply to informal reports. They should contain only facts, presented in a succinct and logical way. Important features to include are the date, the title and the name (and status) of the person making the report. They should begin with a simple statement of the relevant facts and/or circumstances. It can be helpful to number or letter each item.
If there are circumstances in which your opinion has been requested, your opinions would then form the second half of this report. If data and/or diagrams would help the reader, they should be included. The same criteria apply to these diagrams as apply in reports of experiments.