Summarize this article in one sentence.
There are different reading level systems you can choose from, like the DRA leveling system, the Lexile leveling system, and the Scholastic Guided Reading leveling system. Choose a system and stick with it so kids aren't confused when they're looking for a book to read. If you’re using a smartphone app or online database that gives you reading levels for a different system than the one you’re using, convert the levels to your system using a conversion chart at http://teacher.scholastic.com/products/guidedreading/leveling_chart.htm. That way kids can easily tell what reading level the book is when they pick it up. Write the reading level for a book on a label and stick it to the front or back of the book. Or, if you don’t feel like writing out all the labels, use different colored stickers and make a chart that explains what reading level corresponds with each color. Have one bin or shelf be for the easiest reading level, another bin or shelf be for the next reading level up, and so on. This will make it easier for kids to find books that are at their reading level. You can even label the bins or shelves with their corresponding reading level so there’s no confusion.

Summary:
Stay consistent with the leveling system you use. Label the books in your library with their reading level. Separate the leveled books in bins or on bookshelves.