Thomas and Julie wanted to find out which material would insulate their teacher's coffee cup and keep the coffee hot for the longest period of
time. They first wrapped her cup with bubble wrap and recorded the
temperature of the coffee once every 15 minutes for 2 hours. They
repeated the investigation, this time using newspaper instead of bubble
wrap, but they got the same results for both materials. Which of the below
is their control or constant variable?
the type of insulation
the temperature of the coffee
the type of coffee cup
The students conducting the experiment