A student investigated the effect of wind on body temperature regulation (heat loss).
They set up two identical glass beakers, each containing a thermometer, as shown in the diagram below.
Hot water was added to both beakers.
Beaker A was placed directly in front of a running electric fan.
Beaker B was placed in still air (away from the fan).
The temperature of the water in each beaker was recorded every minute for 10 minutes.
State two variables that would need to be controlled in this investigation to ensure a fair test.
