Answer:
The two dry sand samples are examined by changing one parameter. The independent variable, the one that is intentionally manipulated between the two samples, is the
✔ mass of each sample
.
Besides the amount of material, there is also another variable that is manipulated within each of the two mass groups and represented as three types. This independent variable is the
✔ type of material used
.
In each case, the dependent variable, the one that you measure the response in, is the
✔ temperature over time
.