This is a 2-in-1 book for readers aged 7 to 11 years old. In the fiction text, Isaac and his friends need to defeat the giant toxic slugs that have taken over the city. In the non-fiction text, find out about super-slimy (and stinky) animals. Isaac and the Toxics: Toxic Slugs Attack is at Oxford Reading Level 6. It is a fully-decodable book for pupils who are working below expected standard in their reading. The Readerful Rise series ensures that older struggling readers have high-low books with age-appropriate content and topics, that look like the books their peers are enjoying, but are written at a level they can read successfully.