Answer: Pour the mixture through a paper filter
Explanation: The utilization of the first technique, involving boiling the mixture to promote evaporation of water, proved ineffective for the student to achieve successful separation of gravel from the water. Subjecting the aforementioned mixture to boiling conditions would result in the molecular dispersion of water molecules leading to their evaporation, thereby rendering the gravel as the residual solid component. However, it is pertinent to note that such technique is not efficacious in the separation of gravel from water. The presence of additional solid particles and debris from the original mixture would result in the continued mixture of gravel with said components, thereby rendering the gravel not entirely devoid of water.