Dig a hole 50cm deep.
Bury the thermometer in the hole with the string sticking out and leave it overnight.
The next day, carefully dig up the thermometer. Read the temperature quickly.
What was the temperature down in the soil?
What is the temperature of the air?
Bury the thermometer again and repeat the readings at the end of the day.
By how much did the soil temperature changed?
By how much did the air temperature change?
Why might this benefit an animal?
(Adapted from Johnson, J (1990) Outside the Classroom: Grades 3-4, Educational Supplies Pty. Ltd. Brookvale, Australia)