You’ve spent hours on your writing project. Spellcheck 
hasn’t underlined any errors, and you’ve said what you set out to say. Before your teacher even looks at it s/he says to rewrite. What? Why did you put all that time in you wonder? But hear me out. Your teacher has a point. First drafts are rarely ready for prime time.
Revising involves more than punctuation, spelling, and grammar errors. You also want to look at sensory details, sentence flow and variability.
Sensory Detail
You may think you’ve already included all the necessary sensory details. My rule of thumb is to incorporate at least three senses in every scene. In our media-rich environment we tend to describe things in visual and auditory terms. But to immerse your reader add smell, touch, or taste.
Here’s a simple exercise you can do today. Sit outside 
and set a timer for fifteen minutes. Pay attention to how you experience each of your five senses until the timer goes off. When it does, label your paper Sight, sound, smell, taste, touch. See how many things you can list under each heading to describe the time you spent outside. You may be surprised to discover how the senses of smell, taste, and touch manifest themselves. If you feel so inclined, use at least three of the senses to write a narrative of your experience.
Sentence Variability
After checking for SPaG errors, look at sentence variability. Start by going through your paper and highlighting the first few words of each sentence. If every sentence starts subject verb, it’s time to rewrite. Another thing to look for is sentence length. When sentences are all the same length it sets a monotone and will bore your reader, not a good thing especially if this is a school assignment!
Long flowery sentences slow the action down and are best used for description. Short snappy sentences build tension. Look at the before and after example below:
His pencil dented the wood. This gift would be intricate. Dan’s saw followed his trace marks. The pieces were cut by noon.
Now see what happens when you add variety:
His pencil dented the soft pine as he carefully traced the pattern onto the wood. This would be his most intricate gift yet. Dan’s scroll saw followed his trace marks. By noon the pieces were cut.
We get a better sense of the character’s action with the added description in the first sentence. The final sentence sets us up to learn his motivation.
Final Thoughts
When you rewrite, always keep your reader in mind. Ask yourself: am I using enough detail to immerse the reader in the story? Are my word choices strong and evocative? Do my sentences have varying lengths with natural rhythm? In the infamous words of Ernest Hemingway, “writing is rewriting.” Who can argue with that?
