In this lesson, Emma Crewey introduces the concepts of herbivores, carnivores, and omnivores, explaining how different animals consume various types of food for energy. She emphasizes that herbivores eat only plants, carnivores eat only meat, and omnivores eat both, noting that humans are classified as omnivores despite some individuals being vegetarians. The lesson reinforces the importance of nutrition for all living things and encourages students to think critically about animal diets.