Many learners lack the vocabulary to read books. Graded readers such as the Oxford Bookworms series and the Penguin Readers series offer stories at vocabulary levels up to the 3,000 most-common words level. These books let learners move up to higher levels at their own pace. Teenage fiction, such as Percy Jackson, tends to be written at the 5,000 most-common words level. Adult native speakers usually know 10,000-20,000 common words, so (higher quality) newspapers, magazines, and books will be written at the 10,000 common-words level.

There are a lot of books to help beginner level students learn English. 1. Harry Potter series by J. K. Rowling 2. Artemis Fowl series by Eoin Colfer 3. Percy Jackson and the Olympians series by Rick Riordan