Have you ever seen a bird so small that you weren't sure that it was a bird? It was probably a hummingbird Written for students in grade 3, Hummingbirds helps students find out more about hummingbirds. Students see many beautiful pictures of different kinds of hummingbirds in the book. This 22-page book includes a glossary of bold-faced vocabulary words, reading activities, an index of terms, and an answer key.