These levelled non-fiction books feature video content, project work and critical-thinking activities. Each book asks a range of BIG questions on STEM topics from nocturnal animals to building bridges, developing children's language, communication and investigation skills. Space, a Level 4 Reader, is A2 in the CEFR framework and supports YLE Flyers exams. The longer text is made up of sentences with up to three clauses, more complex past and future tense structures, modal verbs and a wider variety of conjunctions.