Neuroscience For Kids suggests examining cereal to develop a science project. Finding out whether or not generic cereals are the same as brand name cereals is a legitimate question that can be analyzed scientifically. Students write down their guess or hypothesis. Performing taste tests, seeing which cereal gets mushy with milk, and comparing ingredients and prices can be done quickly within a time crunch. All the information needs to be written down and conclusions presented. Steve Spangler proposes proving whether or not there is metallic iron in breakfast cereals. After the guess is written down, students can test their hypothesis by crunching cereal into a fine layer and using a strong magnet to see if they stick. Another method of testing if the magnet isn't very strong is putting a few flakes on top of still water and seeing if the magnet can pull the flake to the edge. This experiment can be demonstrated at the science fair and doesn't require written analysis.
Science Buddies recommends students develop a question on which fruit seeds are best designed for wind dispersal. After documenting the guess, the student, using a fan, drops different types of seeds, individually, in front of the fan in the same place and then measures how far the seeds flew with a measuring tape. The student presents the results in chart form. Another variation would be to purchase an array of fruits. The testable question would ask which fruit carries the most seeds. Students document the guess, cut the fruit in half, count and document the number of seeds in each fruit. The chart and fruits can be brought to the fair to visually show the results. Both of these experiments take under an hour.
In this experiment, recommended by Science Buddies, students ask how deforestation affects greenhouse gasses. After writing down their hypothesis, they take two jars and place a small plant inside one jar, leaving the other jar empty. They place a thermometer inside both jars and securely place a lid on top of both jars. The jars are set in a sunny window for at least a few hours. After recording the temperatures along with any other observations, the student uses the data to see if he surmises any effect on greenhouse gases from deforestation. As long as the sun is cooperating, this project can be completed in one afternoon.