- 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
- Number each battery so you can tell them apart.
- Measure each battery's voltage by using the voltmeter.
- Put the same battery into one of the devices and turn it on.
- Let the device run for thirty minutes before measuring its voltage again. (Record the voltage in a table every time it is measured.)
- Repeat #4 until the battery is at 0.9 volts or until the device stops.
- Do steps 1–5 again, three trials for each brand of battery in each experimental group.
- For the camera flash push the flash button every 30 seconds and measure the voltage every 5 minutes.
- For the flashlights rotate each battery brand so each one has a turn in each flashlight.
- For the CD player repeat the same song at the same volume throughout the tests.
- Write the experimental procedure like a step-by-step recipe for your science experiment. A good procedure is so detailed and complete that it lets someone else duplicate your experiment exactly!
- 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!
How many participants are enough?? Click to find out!