Explain that additional trials are needed to ensure that the results are repeatable.
In prior grades students learned to conduct different kinds of investigations. In grades 4-5 students learn to plan an investigation, which involves first selecting the appropriate kind of investigation to match the question being asked. One type of investigation is a controlled experiment (a "fair test"). Others include systematic observation, field studies, and models and simulations. Students can also collect, display, and interpret data; summarize results; draw conclusions from evidence; and communicate their findings. Students are aware that scientific explanations emphasize evidence, involve logical arguments, and are consistent with scientific principles and theories. Students are also expected to communicate their findings and to critique the investigations of others with respect and intellectual honesty. These capabilities are essential in preparing students for the more extensive and rigorous investigations that they will be planning and conducting in middle school.
Repeated trials are necessary for reliability.