Fill in the blanks to complete the sentences below. 1. ___________are factors whose effect can be tested. 2. There are____________ kinds of variables. 3. Factors that are held constant are called __________
4_________variable is the factor that is changed in the experiment.
5. __________variable is the effect due to the independent variable. 6. To have a fair test, only____________ variable should be tested at a time.
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