Place the copper penny into a known mass of water after various periods of time.
The mass of water has an heat capacity of 1 calorie of heat for each gram of water raised ( or lowered) 1 degree C.
By waiting a set period of time 0 sec 1 sec 2 sec 3 sec 4 sec 5 sec. the amount of calorie absorbed by the water is proportional to the amount of each heat held in the copper. A graph can be made of the number of calories released by the copper versus time.
Taking the temperature known for the bunsen burner as the temperature of the copper at time zero. The heat released by the same mass of copper is proportional to the temperature of the copper at that time.
so the graph of heat released is also a graph of the temperature of the copper versus time. This can be used to determine a rate of the cooling of the copper penny.