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These step-by-step instructions and examples are a great starting place for many homework projects. Follow these steps to break up a big assignment into doable pieces, learn how to efficiently complete each part to get the most out of your time, and organize your work to finish everything when due.
Science Experiment
All science experiments follow the scientific method, the step-by-step process that guides thinking and discovery. Careful adherence to the scientific method assures that other scientists can replicate a given experiment and get the same results.
Make sure you understand the job ahead of you. Review all the information you have about your assignment and verify you can answer the following questions. If you don’t know, ask your instructor.
- By what date are you expected to have your results?
- Are you expected to design your experiment around a particular question or topic?
- Did your instructor provide any guidelines for the experiment?
Every science experiment starts with an observation. You see something and you wonder why it happens; or you see something and wonder if what you think caused it really did.
1. Make an observation. Think about everyday things: Flowering trees bloom in the spring, the remote control doesn’t work when someone stands between it and the television.
Example: You observe that flowers growing in the shadow of your red patio umbrella seem to grow bigger than flowers in the other shady parts of the yard. You wonder if the sun shining through the red fabric of the umbrella has anything to do with it, and decide to investigate the effect of colored light on plant growth.
2. Turn your observation into a question. Make sure you find it interesting—the remainder of your work will be devoted to answering this question.
Example: Do plants grow better in colored light?
Learn more about your question before getting down to planning the experiment.
1. Track down information about your question. Look for library books, periodicals, Web sites, and any other good sources of information.
2. Read, read, read. Familiarize yourself with available information related to your question. Has your question—or one similar to it—been investigated by other scientists? What did they find?
3. Talk to people with first-hand knowledge, such as science instructors at your school, your parents, your friends’ parents, or professionals working in the field of your experiment. Ask them if they can recommend research sources or have suggestions for your experiment.
Example: Because your question is about plant growth, you talk to the plant specialist at the nursery.
4. Fine-tune your question to make it as specific and testable as possible. Now that you’re an expert on your topic, you have a better idea about what you’re looking for and how you’re going to find it.
Example: You now know that your original question, “do flowers grow better in colored light?” is too open-ended. You narrow your question to “do marigolds grow better in red light or in green light?”
Develop your hypothesis—a statement predicting the outcome of your experiment.
1. Based on your research, predict the answer to your question—that is, make an educated guess. You know what other scientists have found, and you know the science behind their results.
Example: From your research, you know that plants perform photosynthesis more efficiently in red light than in green light. Your prediction, then, is that marigolds will grow better in red light than they will in green light.
2. Rewrite your prediction as a statement in an “if/then” form.
Example: If I grow some marigolds in red light and some marigolds in green light, then the marigolds grown in red light will grow faster than the marigolds grown in green light because plants perform photosynthesis more efficiently in red and blue wavelengths of light.
To test your hypothesis, you need to design and conduct an experiment.
1. Identify the goal, or what you want to demonstrate, of your experiment.
Example: Your goal is to test your hypothesis—demonstrate that if you grow some marigolds in red light and some in green light, the marigolds in red light will grow faster than marigolds in green light because plants perform photosynthesis more efficiently in red and blue wavelengths of light.
2. Identify and list your variables. A variable is anything that has an effect on the outcome of your experiment.
Example: You plan to grow marigolds in red and green light to see which grows faster. If you vary the color of the light, the rate of growth will vary. Other factors that could influence the rate of plant growth include soil condition and frequency of watering. You determine the variables are:
- Light color
- Rate of growth
- Soil condition
- Watering frequency
3. Design an experiment that restricts as many variables as possible. Your goal is to eliminate all but two variables—the independent variable (the one you plan to manipulate) and the dependent variable (the results that change when you manipulate the independent variable).
Example: You want to grow marigolds in red and green light to see which one grows faster. Your independent variable is light color. Your dependent variable is rate of plan growth. To eliminate all the other variables (soil condition and water), you will plant them in identical potting soil and water them the same measured amount at the same time.
4. Write a procedure plan—that is, exactly how you plan to test your hypothesis. Include a detailed description of how you will control all but the dependent and independent variables, how and when you will manipulate the independent variable, and how and when you will measure the dependent variable.
Example:
1. Fill two identical potting flats with potting soil from the same bag. Place 12 marigold seeds in each flat, evenly spaced. Cover with 1/4 in of potting soil. Water each with 8 ounces of water.
2. Place one flat under a flexible-arm reading lamp with a red, 60 watt light bulb. Adjust lamp so that it is 14 inches above the surface of the soil.
3. Place the other flat under a flexible-arm reading lamp with a green, 60 watt light bulb. Adjust the lamp so that it is 14 inches above the surface of the soil.
4. Turn on lamps and leave them on for the remainder of the experiment.
5. After the seeds have sprouted, number and label the plants in each flat
6. Exactly one week after planting, measure and record the height (in millimeters) of each seedling, sprinkle each flat with 16 ounces of water.
7. Continue watering and recording measurements at regular weekly intervals for 6 weeks.
8. At the end of the 6-week period, compute weekly and final average heights of the marigold in each group. Compare results.
5. List the materials you’ll us to conduct your experiment.
Example: To conduct your marigold experiment, you’ll need:
- Marigold seeds (24)
- Potting soil
- Potting flats (2)
- Lamp on flexible arm (2)
- Red light bulb (1)
- Green light bulb (1)
- Watering can with measurement grid
- Metric ruler
- Paper and pen for recording data
1. Gather and assemble all necessary materials. Check each item off your materials list so you don’t forget anything.
2. Reread your procedure, ensuring that you remember each step.
3. Prepare and label empty data tables for recording data.
1. Follow your documented procedure to the letter.
2. Collected measurements and record your data in pen—not pencil—in your empty data tables.
3. Note—also in pen—any observations you make during your experiment. What did you see? What did you hear? Did you notice any unusual odors? Did anything interfere with your experiment or data collection?
Congratulations, you’re finished with your experiment!
For help with writing up your findings, see Lab Report.
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