Five of the most common science fair projects are making a baking soda and vinegar volcano, creating a vegetable battery, formulating invisible ink, growing crystals and measuring the effects of tooth decay. These are common science fair projects not only because they are simple to perform, but because they are also informative, educational and fun.
One of the most common science fair projects is to create a volcano using baking soda and vinegar. Due to an acid-base reaction, when the baking soda and vinegar are combined, it creates an excess of carbon dioxide, which foams up and flows over the side of the container just like a volcano. Red food coloring helps create the effect of real lava.
Building a vegetable battery is another common science fair project. A potato is a popular choice for this project, as is a lemon (although this is technically a fruit). The basis of this project is that certain fruits and vegetables contain electrolytes that can transmit an electric current between two galvanized pieces of metal. This experiment calls for a lemon, potato or other piece of produce that can transport a charge, a galvanized nail, a copper coin and a small light bulb to be lit up by the power of the vegetable battery.