Final answer:
The experimental design principle demonstrated by repeating an experiment with different teachers or times is Replication, which confirms result reliability.
Step-by-step explanation:
The principle of experimental design that is demonstrated by repeating an experiment several times with different teachers or at different times of the year is Replication. Replication is crucial as it ensures that the results of an experiment are reliable and not just due to chance or a one-time occurrence. By replicating the experiment with different variables such as teachers and times of the year, researchers can confirm that any observed effects on test scores are consistent and not due to external factors. This principle is part of the foundation of a well-designed scientific study because it helps provide convincing evidence that the results are due to the variable being tested - in this case, the effect of the time of day on science test scores.
The experimental design principle being exemplified in this scenario is D. Replication. Replication involves repeating an experiment multiple times to validate the results and ensure their reliability. In the context of the study on the effect of time of day on science class test scores, conducting the experiment with different teachers or at different times of the year would involve replicating the experiment to verify the consistency of the findings.