Eighth-grade students have probably heard about the greenhouse effect, but this project will show them exactly how the gases in the atmosphere can affect the temperature of the air. Make a wooden frame and place it in a grassy area so that the frame is flush with the ground. Cover the frame completely with clear plastic. Place one thermometer next to the frame in the grass, and place another thermometer inside the frame under the plastic. Measure the temperatures several times a day for a week to determine whether or not the plastic traps heat within the frame.
Eighth graders can use this science fair project to study local weather patterns. They will also get experience in reading and illustrating maps. The students will make predictions using an anemometer, barometer, wind vane and thermometer. They should take the measurements each day and create a weather map based on their observations. Students can also study the clouds and incoming weather systems to make weather predictions. By studying their observations, the students can predict the weather for the next two days. They can also check the weather forecast on television to see if their predictions are accurate.
Oil spills have had significant impacts on wildlife. Encourage eighth graders to study just how quickly the damage can spread by testing the factors that affect how oil moves through water. Add motor oil to a container of water. Use a ruler to make waves or turn a fan toward the water. Students can also test water temperature to see if it affects how quickly the oil moves. A ruler or a line on the container can be used to indicate the level of the dispersion.
Use an onion to show how DNA can be extracted from cells. Blend a chopped onion and add liquid detergent and salt. Strain the juice thoroughly using a coffee filter. Stir meat tenderizer into the strained juice and pour the solution in a tube with cold ethanol. Once the solution has stopped bubbling, students will be able to see the DNA of the onion floating on the top.