Grab a book and hold up your hand
Put down a finger for every hard word you find.
0-1 fingers down- This book is too easy for you!
2-3 fingers down- This book is just right for you!
4-5 fingers down- This book is too hard for you!
Reading books that are too easy is okay. This lets you read for enjoyment and allows you to practice obeying punctuation which is important for good fluency.
Having another child or adult at home read a book that may be too hard for you is okay as well. This allows you to listen to the story and have a discussion about it afterward.