i'm not very sure about this but i think it is
input - temperature reading
processing - database lookup
output - actuator to control temperature
i'm not 100% sure because i don't take computer studies.
Temperature reading will be a process,not input... input will probably be power inserted.
Processing will be temperature sensor check to see if its too hot, powder sensor to see if the powder is sufficent.
Tell me something, which passpaper did you get this from?