As writers, we have a lot of decisions to make. Which words do I choose? What setting is best? Who should tell the story? How do I describe this situation? We can also make a lot of mistakes that will be fixed in the editing process. But the worst mistake a writer can make is underestimating their reader.
As a teacher, I see time and time again that kids really do get things when they read. They visualize, infer, draw conclusions about characters, and think while they read. So, we shouldn't water down our novels because we write for middle grade or young adult audiences. Our novels should be as rich and complex as an adult novel, just minus the adult themes (or some of them).
So, if you want to use a certain word but worry that younger readers won't understand, stop yourself from over explaining. They really do get it. If they can sound it out, they can understand. And in most cases, there's an adult nearby who can help. Plus, they are learning from you in the process.
When you're tempted to describe everything to the nth detail, stop yourself. Keep your descriptions neat and tight, don't ramble. That actually makes young readers abandon books. I watch my students when I do a read aloud and when it comes to long descriptions, they listen to get the gist, then they tune me out if the description becomes too long. They want action! Young readers would rather you spend four paragraphs on the action scenes than the description scenes. Trust me!
Here are some examples of writers underestimating their readers: (examples courtesy of http://www.culturefeast.com/dont-underestimate-your-readers/)
EXAMPLE: The judge sentenced the thief to six years in jail.
BETTER: The judge sentenced the thief to six years.
EXAMPLE: The house was painted green in color.
BETTER: The house was painted green.
EXAMPLE: The whistle had too loud a sound.
BETTER: The whistle was too loud.
EXAMPLE: He was over two hundred pounds in weight.
BETTER: He was over two hundred pounds.
EXAMPLE: Each tire lasts for a predetermined number of miles when the car is driven.
BETTER: Each tire lasts for a predetermined number of miles.
JK Rowling once said in an interview that she received several rejections for Harry Potter that simply said this book is to much for children, it's too wordy, there are too many pages, etc. Her response to them was brilliant. She said, "I'm going to write the book the way I want to write it. Publishers today underestimate the reader, especially young readers, and I choose not do that."
So, here's the advice. Write what you want to write, write it the way you want to write, and never, ever underestimate your reader!