A good science fair project involving dogs is finding out if a dog can differentiate between words or even simple sounds in human language. Another simple project is testing colorblindness in dogs.
The materials needed for the language project are three commands the dog knows well, a notebook and a pen. The person conducting the project takes those commands and varies them slightly, like saying "may" instead of "stay," while using the same tone of voice as the normal command. The person says the commands five times in a row, notating the reactions. Next, the experimenter takes three words that sound nothing like the original commands and uses the same tone of voice. Results vary, but most dogs do understand and differentiate 100 or more words because of the reinforcement they receive when they respond to commands.
The materials needed for the colorblindness project are a camera, multiple colors of construction paper, black and white film, three identical glass jars and some dog treats. The construction paper is numbered and photographed in the same lighting with the black and white film. Colors that resemble the same shade of grey are picked and placed around the first two glass jars, with the third jar covered by paper with a shade much lighter or darker than jars one and two. The dog is commanded to come to jars one and three, with two in a non-visible place, and only receives a treat for going to jar one not jar three. After repeating this many times, the dog is trained to choose jar one.
Jar three is replaced by jar two and the dog is commanded to come to the jars again. The jars should rotate places after every command to test if the dog differentiates between the colors. If it chooses jar one every time, it can tell the difference between the shades. The results should find that dogs distinguish between blue, purple, yellow and different shades of grey. They cannot tell the difference between green, yellow, orange and red.