Most holidays have symbols, such as a heart for Valentine's Day and a jack-o-lantern for Halloween. Let's explore other holiday symbols The D as de Descubrimiento (Discovery Days) series is perfect for young learners in prekindergarten through grade 2. These 16-page books give readers an accessible introduction to nonfiction reading. Color photographs and fun, factual examples will grab the attention of young readers and help strengthen reading comprehension skills.