Set up an experiment to measure gain and loss of heat by water, sand and air.
Take two beakers and fill them with water and sand, respectively. Take a closed bottle and place a thermometer in it. Keep these three in sunlight for three hours. Now, measure the temperatures of the three containers.
You will observe that the temperature of water is less than the temperature of sand, as sand gets heated by the sun faster than water. Also, the temperature of air in the closed bottle will be higher than the normal temperature of air in open because of the greenhouse effect.
Also, measure the temperature in shade, as temperature in direct sunlight will not be uniform.