Selena noticed that the sand at the beach seemed much warmer than the water. She wondered whether that was because water took more enrgy to heat up than land.

I don't understand. What I would like to know here, is what would be the dependent and independent variable. And what does constant factor mean ??

In this scenario, the independent variable is the type of surface being compared, which is the land (sand) and water. The dependent variable is the temperature of each surface. The researcher, Selena, is comparing the temperatures of the sand and water to determine if one surface absorbs and retains heat more effectively than the other.

A constant factor, also known as a controlled variable, refers to the variables that are kept constant or consistent throughout the experiment. In this case, the constant factors might include factors such as the time of day the measurement is taken, the location on the beach where the measurements are made, or the instruments used to measure temperature. Keeping these factors constant ensures that any differences observed in temperature can be attributed to the differences between the sand and water, rather than other external factors.

To investigate whether water takes more energy to heat up than land, Selena could conduct an experiment by measuring the temperature of sand and water at the same time and in the same location. She could use a thermometer to measure the temperature of the sand, and a separate thermometer to measure the temperature of the water. By comparing the two measurements over a period of time, she can determine if there is a difference in how quickly each surface heats up or cools down.