Observe how rodents use their sense of smell as a navigation tool with a maze experiment. For a science fair, middle school students can build a simple maze with cardboard walls arranged in the top of a cardboard box, or purchase a maze specifically designed for rodent experiments from an educational store. During the fair demonstration, the child places a mouse in the maze and records on a chart how long it takes for the rodent to navigate to the other side. In a second trial, the student places a piece of food at the end of the maze and repeats the activity, recording the time on the chart display. The student then describes how the animal's sense of smell aided it in navigating the maze more quickly. Another demonstration might involve dragging the food through the correct maze path first, or using the animal's bedding as the scent object.
To experiment with a snake's sense of smell, a child presents a pet snake several scent-based items over the course of several days or weeks and observes the snake's "sniffing" behavior. For example, a garter snake will flick its tongue aggressively when presented an appropriate food item like live worms, but it will also investigate non-food items with its tongue. Try introducing an object that smells like a snake predator, like a feather from a bird or a plastic toy used by a cat. The student writes observations comparing the snake's tongue behavior with food objects and non-food objects. At the science fair, display a poster comparing how long the snake interacted with the objects and the similarities in "sniffing" or "licking" behaviors even when the object was not food. Since the snake uses its tongue to investigate both food and non-food, children conclude snake tongues are used for sniffing rather than tasting.
Animals often use their sense of smell to identify and locate food items. Children can compare different animals' or breeds' ability to identify food with a hidden food experiment. The child places a safe, edible treat in one of three identical opaque plastic containers with lids. When the containers are presented to the test animal, time how long it takes the animal to identify, based on behavior cues like scratching or ignoring the other containers, the container with the treat. Try the experiment with different animals like dogs, cats and mice and compare not just their times but their general sniffing behaviors. Students chart the times on a bar graph to compare each animal and make conclusions regarding which animals have the most effective sense of smell.
Different scents stimulate different animal behaviors. To observe how animals interact with different kinds of smells, collect several groups of related objects. Include three kinds of fruits or vegetables, three kinds of meat and three items belonging to familiar or unfamiliar people or animals. Keep the items in individual containers. To conduct the experiment, place each container from the first item group in a separate corner of a room. Introduce the dog to the room. The child times how long the animal interacts with each container and what types of other behaviors, like whining, digging or growling, the animal exhibits. Repeat the activity with the other groups of items. The child then creates a chart comparing the animal's behaviors between and within each group of items. The child might make conclusions about the animal's preference for food or reaction to objects that smell familiar versus objects that are unfamiliar.