Goldilocks and the Three Bears is a well-known fairy tale and provides a great opening for scientific inquiry.
Whatever version of Goldilocks and the Three Bears you prefer, you'll come to the spot when Goldilocks goes to eat the porridge. She finds that Papa's porridge, in the largest bowl, is too hot; Mama's porridge, in the middle-sized bowl, is too cold; and the Baby's porridge, in the smallest bowl, is just right.
Does this part of the story make sense, scientifically? Would the largest vessel keep something the hottest? What about the smallest vessel keeping it warmer than the medium-sized one?
It's easy to test it out for yourself!
You'll need 3 jars/bottles/beakers, each a different size. If I were at school, I would use three different sized beakers. Because I'm working from home, I used three different sizes of Mason jars: a quart jar, a pint jar, and a half-pint jar. You'll also need a thermometer. I used a candy thermometer, because that's what I had at home.
Fill each of the jars with hot water. However hot you can get it to come out of the tap is fine, it's not necessary to heat it further.
Take a temperature reading right away, so you know your starting point.
For younger students:
Set a timer for 15 minutes and when it sounds, take a temperature reading for each jar. If you wish, you take an additional reading after another 15 minutes.
For older students:
Have the students, working in lab groups, take and record the temperature of each jar of water at regular intervals (1, 2 or 3 minutes). These students can then graph their data, which will show the rate at which heat is lost from each vessel.
I started with water that was 125 degrees Fahrenheit. After 15 minutes, I had the following data:
Papa (Quart jar): 115 degrees
Mama (Pint jar): 109 degrees
Baby (Half-pint jar): 100 degrees
After completing the activity, graphing and drawing conclusions, students can re-write the tale, incorporating what they learned from the lab.