The purpose of writing is to show or explain how something actually works a state reason some phenomenon Explanations to answer questions like how or why for a how explanation or sentence is going to be like how does the pump work ? how are mountains formed and also for why it is like asking a question example why does some sticks sink and some sticks float? And why do we need food.
Explanation writing is a logical sequence that lets the reader understand much more easier and then you can finish your work faster and also explain what you felt and your emotions that gives them a clear thought to know what they are doing.
And when you use your explanation think of what you are going to write sometimes even the writer puts in some of his feelings in the story. And when you use your punctuation and full stops question marks use them while your writing instead of finishing your work and then going back and edit.
Most purposes about writing is putting in all details. like jump starting a car,licking ice cream for days use your adjectives,and writing is just like reading when you write throungth you also read to just at the same time but whispering it just normal if you try write without talking it would be in your head.
Perhaps you can even write with in you maths when somebody says a question example you could say if 2 + 3 is 5 then what is 2 x 3? See i used word and numbers as a question not like just saying what are you up two.