A group of students want to see if they can make an electromagnet that shows evidence of an electrical/magnetic field. They find a picture in a science book of how to make an electromagnet. First, they gather a battery, some copper wire, and a nail. They wrap the wire around the nail and attach the ends of the wire to the battery. They find a bunch of stuff in a desk: paperclips, erasers, stick pins, and so on. They put the electromagnet near each object and see what happens. Some objects move, and some don’t.
How will you evaluate the experimental design? What should you do first?
Remember that you are trying to decide whether the experiment provides evidence of
magnetic/electrical fields. Would you answer: “Yes, the experiment would provide evidence of magnetic/electrical fields? Or would you answer: “No, the experiment would not provide evidence of magnetic/electrical fields.”
Next, you are looking for any area(s) where the plan could be modified to better meet its goal. Evaluate all the areas of the experimental design:
Hypothesis: What is the hypothesis of the experiment? Decide if the experiment is able to test the hypothesis. If so, how?
Materials: What are the materials listed in the experiment? Could the description of materials needed be improved? How?
Methods: What are the methods listed in the experiment? Could the directions be improved? How?
First, before evaluating the experimental design, I would answer: "Yes, the experiment would provide evidence of magnetic/electrical fields."
Hypothesis: The hypothesis of the experiment is likely that the electromagnet will create a magnetic field that will attract certain objects such as paperclips, erasers, and stick pins. The experiment is able to test this hypothesis by observing the behavior of the objects when the electromagnet is brought near them.
Materials: The materials listed in the experiment are a battery, copper wire, a nail, paperclips, erasers, and stick pins. The description of materials needed could be improved by providing specific details such as the type and size of battery, the gauge of copper wire, and the size of the nail. This would ensure consistency among different trials of the experiment.
Methods: The methods listed in the experiment are to wrap the wire around the nail, attach the ends of the wire to the battery, and then test the electromagnet on various objects. The directions could be improved by specifying the number of wire coils around the nail, the polarity of the battery connection, and the distance at which the electromagnet should be held from the objects. These details would help ensure a more controlled and reliable experiment.