Usually, title of an explanation contains how or why. It may also uses a question mark. For example:
General statement is found in the first paragraph. It introduces or identifies the scientific or technical phenomenon. It gives the audience a short introduction to the event or thing and an understanding of the type of text that is to follow.
This part describes or explains causal or sequential relationship. Causal relationship is mostly used in explaining why something happens, while sequenced ones are used in explaining how something works or happens. Sequences often develop by explaining how the events happen over a period of time: first this happens and then this is followed by the next event. Generally there is no human involved in the process of events.
An optional concluding statement can connect or conclude the explanation.
Labelled diagrams and flow charts can be used to clarify information or to add additional information not included in the explanation.
For example, the diagram on the left is made to add the understanding of an explanation text describes how a volcano explode