High School Science Fair Projects

These projects should use the scientific method

Woman working in chemistry lab
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Coming up with a high school science fair project idea can be challenging. There is fierce competition for the coolest idea, and you need a topic appropriate for your educational level. Below are science fair project ideas arranged by topic, but you might first take a look at ideas according to education level:

High School Projects

High school science fair projects are the hardest in that almost everyone has to do one, and it's usually for a grade. You want a topic that makes the judges take notice. Consider topics addressed by others and ask yourself what questions are left unanswered? How could they be tested? Look for problems in the world around you and try to explain them or solve them. Demonstrations and models might be acceptable at earlier educational levels, but in high school the scientific method should be the basis for your scientific exploration. Here are some ideas:

  • How safe is your microwave oven? Compare the growth of a plant or germination of seeds placed near the oven with those grown under the same light/temperature conditions farther from the appliance.
  • Will bottled water turn green (grow algae) if you leave unopened bottles in the sun? Does it matter which brand you use?
  • How much is the interior of a car cooled if a light-blocking windshield cover is used?
  • How sterile is contact lens solution and how long does it stay sterile? See how long it takes for mold, fungi, and bacteria to culture saline. How sterile is the inside of a person's contact lens case?
  • Can you make a musical instrument that can play a complete scale? Examples might include a rubber band harp or flute from clay, wood, or plastic.
  • Can a black light detect invisible stains?
  • What type of plastic wrap prevents evaporation the best?
  • What plastic wrap prevents oxidation the best?
  • Are night insects attracted to lamps because of heat or light?
  • What type of car antifreeze is safest for the environment?
  • Do different brands of orange juice contain different levels of vitamin C?
  • Does the level of vitamin C in orange juice change over time?
  • How effective are natural mosquito repellents?
  • Does magnetism affect the growth of plants?
  • Do oranges gain or lose vitamin C after being picked?
  • How does the sugar concentration vary in different brands of apple juice?
  • Does storage temperature affect the pH of juice?
  • Does the presence of cigarette smoke affect the growth rate of plants?
  • Does eating breakfast have an effect on school performance? Does it matter what you eat?
  • Do the same types of mold grow on all types of bread?
  • Does light affect the rate at which foods spoil?
  • Do foods containing preservatives stay fresh longer than foods without them?
  • How does time or season of harvest affect the chemistry and nutritional content of food?
  • How long do home hair-coloring products hold their color? Does brand matter? Does type of hair affect colorfastness? How does previous treatment (perming, previous coloring, straightening) affect initial color intensity and colorfastness?
  • Do all dishwashing detergents produce the same amount of bubbles? Clean the same number of dishes?
  • Is the nutritional content of different brands of a vegetable (e.g., canned peas) the same?
  • How permanent are permanent markers? What solvents (e.g., water, alcohol, vinegar, detergent solution) will remove the ink? Do different brands/types of markers produce the same results?
  • Do plant-based insect repellents work as well as synthesized chemical repellents?
  • Do consumers prefer bleached paper products or natural-color paper products? Why?
  • Is laundry detergent as effective if you use less than the recommended amount? More?
  • Is bottled water more pure than tap water?
  • How does the pH of juice change with time? How does temperature affect the rate of chemical changes?
  • Do all hair sprays hold equally well? Equally long? Does the type of hair affect the results?
  • How does the rate of evaporation of the crystal-growing medium affect the final size of the crystals?
  • You usually heat water or another liquid to dissolve a solid to grow crystals. Does the rate at which this liquid is cooled affect the way the crystals grow?
  • What effect do additives have on the crystals?
  • How do different fertilizers affect the way plants grow? There are lots of different types of fertilizers containing varying amounts of nitrogen, phosphorus, and potassium in addition to other ingredients. You can test different fertilizers and see how they affect the height of a plant, the number or size of its leaves, the number of flowers, time until blooming, branching of stems, root development, or other factors.
  • Does using colored mulch have an effect on a plant? You can look at its height, fruitfulness, the number of flowers, overall plant size, the rate of growth, or other factors.
  • How do different factors affect seed germination? Factors that you could test include the intensity, duration, or type of light, the temperature, the amount of water, the presence/absence of certain chemicals, or the presence/absence of soil. You can look at the percentage of seeds that germinate or the rate at which seeds germinate.
  • How are plants affected by the distance between them? Look into the concept of allelopathy. Sweet potatoes release chemicals (allelochemicals) that can inhibit the growth of plants near them. How close can another plant grow to a sweet potato? What effects does an allelochemical have on a plant?
  • Is a seed affected by its size? Do different size seeds have different germination rates or percentages? Does seed size affect the growth rate or final size of a plant?
  • How does cold storage affect the germination of seeds? Factors you can control include the type of seeds, the length of storage, the temperature of storage, and other variables, such as light and humidity.
  • What conditions affect the ripening of fruit? Look at ethylene and enclosing a fruit in a sealed bag, temperature, light, or nearness to other pieces of fruit.
  • How are different soils affected by erosion? You can make your own wind and use water to evaluate the effects on soil. If you have access to a very cold freezer, you can look at the effects of freeze and thaw cycles.
  • How does the pH of soil relate to the pH of the water around the soil? You can make your own pH paper, test the pH of the soil, add water, then test the pH of the water. Are the two values the same? If not, is there a relationship between them?
  • How close does a plant have to be to a pesticide for it to work? What factors influence the effectiveness of a pesticide (rain? light? wind?)? How much can you dilute a pesticide while retaining its effectiveness? How effective are natural pest deterrents?
  • What is the effect of a chemical on a plant? Factors that you can measure include rate of plant growth, leaf size, life/death of the plant, color, and ability to flower/bear fruit.