Alicia Z. Klepeis 
Nocturnal and Diurnal Animals Explained [PDF ebook] 

Why do some animals sleep during the day and others sleep at night? The answer is that each species chooses when the best time is to eat and avoid being eaten. Students can explore the characteristics that make a species thrive in daylight or in the dark, take a quiz to test their understanding, and learn about the animals who come out in the twilight hours between day and night.