I always loved pet week as a teacher. "My cat had puppies!" was my favorite one-liner.
Even for children who do not have pets at home, this week is a developmental boost. All of the children are talking about pets and learning about the science of living things! They are learning about skin coverings (fur, scales, feathers, etc.), and discussing things living creatures need to survive and thrive (food, water, shelter, and care). Inevitably someone knows someone who has lost a pet, which leads to discussions about the life cycle. While these talks may seem trivial, they are the first steps towards caring for and coping with other relationships in real life!