Final answer:
A medical thermometer is a closed system and can be transformed into an isolated system by thermally insulating it from its surroundings.
Step-by-step explanation:
A medical thermometer can be considered as a closed system. A closed system can exchange energy but not matter with its surroundings. In the case of a medical thermometer, it does not exchange matter with its surroundings, as it only measures the temperature of the body without any transfer of matter.
To transform a closed system into an isolated system, it would need to be thermally insulated from its surroundings. An insulated thermos containing hot coffee approximates an isolated system, as it minimizes heat transfer between the system (coffee) and the surroundings.