Dog and cat foods are big money-makers. Some companies even create "fresh" pet foods and store them in the refrigerated section of the grocery store. See if your child's favorite pet really does prefer fresh food by making them a healthy dinner each night. Help your child research which foods are good for dogs and cats to eat, and then prepare a meal. Compare the dog or cat's appetite for the fresh food versus the dry bagged food. Time how long it takes for the pet to eat the food and whether or not the pet seems to eagerly anticipate being fed. You can even extend this to fish. If you fish as a family, try experimenting with which type of bait works best for different types of fish.
It might seem like your child's cat sleeps all day, but maybe it just takes a lot of short "cat naps." Help your child track the sleep and activity cycle of her pet. The pet can be a cat, dog, hamster or any other type as long as sleeping is easy to detect. You may need to set up a video camera to do this. If there is more than one pet in the family, consider tracking more than one. Or, if your child would like to study the habits of a wild animal, take a trip to your local zoo and see if your child can interview a big cat trainer or elephant trainer about the animals' sleep cycles. Center the research around a question about whether the animal has different sleep habits than a human does, and why.
Young children might be curious about the life cycle of an animal. In this case, you could center a science project around raising a critter such as a butterfly, fish or frog. Center the question about how long it takes for a tadpole to fully become a fully developed young frog, or how long each stage of a caterpillar's metamorphosis lasts. Compare it to the life cycle of a human. Such a project not only teaches your child about the animal chosen, but it also teaches important skills that revolve around forming responsible habits.
Animals are like people. Or are they? Think about traits humans have, and then use that to come up with a question that you can center a project around. For example, people are left- or right-handed. A child might wonder if dogs favor their left or right front paws. You might help your child place a treat in front of the dog and see if he reaches for it with his left paw, right paw or just bypasses the paws and uses his head -- and mouth. Or, if your child wonders whether cats can remember things, test your cat's memory by hiding her favorite toy in her presence and seeing if she remembers later. A trip to the zoo to talk to an expert can answer questions about whether wild animals in captivity can learn and perform tricks.