Penguin Readers is an ELT graded reader series for learners of English as a foreign language. With carefully adapted text, new illustrations and language learning exercises, the print edition also includes instructions to access supporting material online. Titles include popular classics, exciting contemporary fiction, and thought-provoking non-fiction, introducing language learners to bestselling authors and compelling content. The eight levels of Penguin Readers follow the Common European Framework of Reference for language learning (CEFR). Exercises at the back of each Reader help language learners to practise grammar, vocabulary, and key exam skills. Before, during and after-reading questions test readers' story comprehension and develop vocabulary. Visit the Penguin Readers websiteExclusively with the print edition, readers can unlock online resources including a digital book, audio edition, lesson plans and answer keys. Unlocking the Universe takes us on a journey through space and time. It starts 13.8 billion years ago with the Big Bang, which led to the stars, the planets and our Solar System. Then it explores our Solar System and other solar systems - the ones we know, and others we have yet to find.