An experiment will be conducted to determine whether children learn their multiplication facts better by practicing with flash cards or by practicing on a computer. Children who volunteer for the experiment will be randomly assigned to one of the two treatments. Because the children's gender may affect the outcome, there will be blocking by gender. After practice, the children will be given a test on their multiplication facts. Why will it be impossible to conduct a double-blind experiment?

Answer: The correct answer is: it will be impossible to conduct a double-blind experiment because the kid will know whether he or she used flashcards or the computer.

Explanation:

In a double-blind experiment both researchers and patients are blinded to some important information about the study. This with the purpose of obtaining the most accurate answers, since many times people's characteristics or ideas might affect the experiment's development and the results. In the given example, it will be impossible to conduct a double-blind experiment because children (patients) are aware of the method (flashcards or the computer) used to obtain the information.