Good eighth-grade science fair project ideas entail experiments that are easy to perform, yet clearly demonstrate a scientific principle. Science project ideas include examining the results of a change in air pressure, assessing the effect of colors on human blood pressure and documenting the effect of different wavelengths of light on phosphorescent material.
Demonstrate the effect of changes in air pressure with a boiled egg, a glass jar and some matches. Hard-boil two or more medium-sized eggs and peel off the eggshells after they cool. Rub some vegetable oil on the egg, then place the boiled egg on top of a glass jar with a narrow opening. The mouth of the jar should be wide enough so that the smaller end of the egg fits into the opening half an inch or less, leaving most of the egg outside the jar. Next, remove the egg and light two matches. When the matches are burning well, drop them into the jar and replace the egg in the opening of the glass jar. The matches will remove some of the air from inside the jar as they burn. As the air heats, it will rise to the top of the jar and escape because the egg does not form a tight seal. The egg will appear to bounce and then will drop into the jar. Did the egg go into the jar because it was sucked in by the decreased air pressure inside jar, or was it pushed into the jar by the greater air pressure outside the jar?
Color and Blood Pressure
Color may affect people emotionally, and some colors are calming while others may stimulate people, according to All-Science-Fair-Projects.com. Does color have an effect on blood pressure? To conduct this experiment, the student will need a computer, 20 participants (10 males and 10 females), and a portable blood pressure monitor. Prepare blank screen displays of the colors blue, red, black, white, green and yellow. Participants are seated one at a time in front of a computer and allowed to relax for 30 minutes. Take the participant’s blood pressure and record it. This is the control reading for that participant. The effect of color on the participant’s blood pressure will be judged according to the control reading. Next, have the participant stare at a blue screen for three minutes and then take a blood pressure reading. Record the findings and wait 15 minutes. Then, have the participant stare at a red screen for three minutes and take another blood pressure reading. Repeat the process until the participant has viewed each color for three minutes. Which colors increased or decreased blood pressure?
Light and Phosphorescence
Phosphorescent material absorbs light wave energy and then releases the energy slowly, which causes the material to glow. Visible light is composed of all the colors of the rainbow, each with a different wavelength. Which color of light will cause phosphorescent material to glow brightest or longest? For this experiment, provide the student with four glow-in-the-dark stickers, a dark room and four lamps. The four lamps should be set up to emit infrared, incandescent, florescent and ultraviolet light. Find a room with no windows. Set up each lamp on a long table so that it is one meter above the top of the table. Place one sticker in front of each lamp and cover it with a piece of heavy cardboard to prevent light from reaching the phosphorescent material. Turn on the lamp and then turn off the other lights in the room. Remove the cardboard covering the sticker under the lamp and start a stopwatch. Leave the lamp on for one minute and then switch it off. Allow the stopwatch to continue running until the sticker stops glowing, then stop the watch. Record the time on the watch and subtract the one minute for which lamp was turned on. The difference is the amount of time the sticker glowed after the lamp was switched off. Repeat the process until all stickers have been exposed and the time recorded. Which light source caused the stickers to glow the longest?