A good hypothesis allows you to then make a prediction:
"If _____[I do this] _____, then _____[this]_____ will happen."

• Background Research Plan

• Finding Information

• How to Write a Bibliography in APA and MLA styles With Examples

• Research Paper

• Your Question

• Laboratory Notebook

• Variables

• Variables for Beginners

• Writing a Hypothesis for Your Science Fair Project

• Experimental Procedure

• Materials List

• Conducting an Experiment

• Repeating a science experiment is an important step to verify that your results are consistent and not just an accident.

  • For a typical experiment, you should plan to repeat it at least three times (more is better).

  • If you are doing something like growing plants, then you should do the experiment on at least three plants in separate pots (that's the same as doing the experiment three times).

  • If you are doing an experiment that involves testing or surveying different groups, you won't need to repeat the experiment three times, but you will need to test or survey a sufficient number of participants to insure that your results are reliable. You will almost always need many more than three participants! See our Science Buddies resource, How Many Survey Participants Do I Need?

  • If your experiment involves machine learning, you won't need to repeat it three times. Machine learning models go through many rounds of training, called iterations, to learn from the data. These built-in iterations and tests are enough to check that your results are reliable but make sure to explain why this process works in your project.

To have confidence that your survey results are representative, it is critically important that you have a large number of randomly selected participants in each group you survey.

https://clincalc.com/stats/samplesize.aspx

Mean: Let's get started.

Median: How to find out how the "average Joe" is doing.

Mode: Who's popular?

Percent: Looking for changes.

Per capita and Rates: When an increase is really a decrease, and other ways people can use numbers to trick you.

Standard Deviation and Normal Distribution: A quick look at the King of Stats.

Survey Sample Sizes and Margin of Error: How not to get suckered by polls and other research.

Regression Analysis: It's all about relationships.

Data Analysis: How to tell if these numbers are really worth writing about anyway.

Statistical Tests: How do I pick the correct statistical test?

Student's T: Is your sample relevant to the larger population it is supposed to represent?

• CD player & a CD (low drain device)

• Three identical flashlights (medium drain device)

• Camera flash (high drain device)

• AA size Duracell and Energizer batteries

• AA size of a "heavy-duty" (non-alkaline) battery (I used Panasonic)

• Voltmeter & a AA battery holder

• Kitchen timer

Experimental Procedure

1. Number each battery so you can tell them apart.

2. Measure each battery's voltage by using the voltmeter.

3. Put the same battery into one of the devices and turn it on.

4. Let the device run for thirty minutes before measuring its voltage again. (Record the voltage in a table every time it is measured.)

5. Repeat step 4 until the battery is at 0.9 volts or until the device stops.

6. Do steps 1–5 again, three trials for each brand of battery in each experimental group.

7. For the camera flash push the flash button every 30 seconds and measure the voltage every 5 minutes.

8. For the flashlights rotate each battery brand so each one has a turn in each flashlight.

9. For the CD player repeat the same song at the same volume throughout the tests.