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?
To evaluate the experimental design, you should first examine the method used by the students to create the electromagnet. Assess if it follows the proper procedure and if the materials are appropriate for the experiment. Consider the following steps for evaluation:
1. Review the picture in the science book: Examine if the instructions and diagram provided are accurate and scientifically sound. Confirm that the students followed the depicted procedure correctly.
2. Evaluate the equipment: Check whether the battery, copper wire, and nail chosen by the students are suitable for the experiment. Verify if the battery has sufficient power, the wire is properly insulated, and the nail is made of ferromagnetic material.
3. Assess the setup: Ensure that the wire is tightly wrapped around the nail and securely attached to the battery. Verify if the electrical connection is adequate and stable.
4. Review the objects tested: Examine if the objects chosen by the students are appropriate for observing the effects of the electromagnet. Consider if they have magnetic properties or if the electromagnetic field generated by the electromagnet is strong enough to induce an effect.
5. Observe the results: Analyze the outcomes of the experiment for each object tested. Record which objects moved and which did not in the presence of the electromagnet. Assess if the results align with the properties of the objects tested and the expectations of the experiment.
6. Consider control groups: If the experiment aims to compare the effects of the electromagnet on various objects, ensure that appropriate control groups are established. This could involve testing objects without the electromagnet to observe any natural movements or magnetic properties.
7. Safety precautions: Evaluate if the students followed safety guidelines during the experiment. Confirm if they wore appropriate protective equipment, handled the materials properly, and took appropriate precautions to avoid hazards.
8. Analyze data: Upon collecting the results, analyze the data to determine any patterns, correlations, or significant findings. Assess if the results provide evidence of the presence of an electrical/magnetic field generated by the electromagnet.
By evaluating these aspects of the experimental design, you can ensure the integrity, reliability, and validity of the students' experiment.