Final answer:
In the context of the student's question, constants in an experiment are variables that are kept unchanged to ensure the reliability of the results. The presumed constants could include the type of equipment used and the duration of the experiment to maintain standardization.
Step-by-step explanation:
A constant in an experiment refers to variables that remain unchanged throughout the study to ensure that the outcome is affected only by the experimental variable being tested. Constants are crucial for maintaining the validity of an experiment. For example, in a study testing the effect of a nutrient like phosphate on the growth of algae, constants might include the volume of water in each tank or the type of equipment used. In the scenario provided by the student question, the constants presumed to be kept among all participants could include various factors such as the type of equipment used and the duration of the experiment, as these would be necessary to ensure standardization across experimental conditions.
It's important to distinguish between constants and variables in experiments. An experimental variable, or independent variable, is what the researcher changes deliberately to observe the effect on the dependent variable. Control variables are those elements that are kept the same throughout all parts of the experiment to enable a fair test of the hypothesis. As such, when trying to discern the constants in a given study or experiment, one must consider the elements that were essential to keep stable in order to measure the effects of the independent variable accurately.