A student investigates how the thickness of an insulating material (measured by the number of layers wrapped around a beaker) affects the rate at which hot water cools.

The following apparatus is available:

• a glass beaker
• a supply of hot water
• a thermometer
• a stopwatch
• a measuring cylinder
• a roll of bubble wrap (insulating material) and scissors

The student can also use other apparatus and materials that are usually available in a school laboratory.

Plan an experiment to investigate how the number of layers of bubble wrap affects the cooling of hot water over a fixed time period.

In your plan, you should:

• draw a diagram of the apparatus used
• explain briefly how you would carry out the investigation
• state the key variables that you would control
• draw a table, or tables, with column headings, to show how you would display your readings (you are not required to enter any readings in the table)
• explain how you would use your readings to reach a conclusion.