METHOD!

I might change my method slightly later on, but this is what I have now:

Method

1. Obtain four balloons of equal size, shape and colour.
2. Inflate all balloons to approximately the same size (diameter of 40 cm). Use a measuring tape to ensure the diameter is approximately 40 cm for each balloon.
3. Place the first balloon in the refrigerator at 0°C and leave it for three hours. Make sure the refrigerator door remains shut for all three hours, to restrict the amount of warm air flowing inside.
4. Place the second balloon in a heated room at 25°C for three hours. Ensure that all doors and windows are shut at all times, to control the amount of cool air flowing inside the room.
5. Tie the third balloon to a fan and leave the fan on for three hours.
6. Place the fourth balloon in a bucket, with a constant stream of water above it, and leave this for three hours also.
7. Retrieve all the balloons from their respective places after three hours, and observe any changes i.e. difference in size, shape, rate of deflation.
8. Record all observations.
9. Repeat steps 1-8.