Axel and his uncle find a note that describes a path to Earth's center! The men climb deep inside a volcano and discover amazing wonders. They also run into danger, which could trap them below the surface forever. These reader-favorite tiles are now updated for enhanced Common Core State Standards s...

Axel and his uncle find a note that describes a path to Earth's center! The men climb deep inside a volcano and discover amazing wonders. They also run into danger, which could trap them below the surface forever. These reader-favorite tiles are now updated for enhanced Common Core State Standards support, including discussion and writing prompts developed by a Common Core expert, an expanded introduction, bolded glossary words and dynamic new covers.