The Orange Dilemma

The students in Mrs. McNally’s class worked together on an experiment about sinking and floating that incorporates values from STEAM curriculum. Sinking and floating are concepts that the Montessori children are already familiar with. To expand upon this lesson, our captivated class learned about the concept of buoyancy. This experiment requires a large glass vase, an orange, and water. 

Before beginning the exercise, Mrs. McNally surveyed the class to gauge their predictions about whether the orange would sink or float. The majority of our group predicted that the orange would sink in the water. We then filled the large glass vase with water to fill it about two-thirds. The curious children carefully placed the orange in the vase.

To their shock and surprise, the orange actually floated! To test the concept of buoyancy further each student participated in peeling the orange. Mrs. McNally asked them to make another prediction based on whether the removal of the peel would affect the orange.

Would it sink or float now?

Several children believed the orange would float again. They felt that the orange would be lighter since the peel had been removed. Surprisingly the orange sank swiftly to the bottom of the vase.  This absolutely mesmerized and shocked the children. They truly believed that the peeled orange would float!

Why wouldn’t it, you ask? A science lesson lies within the peel of the orange. If an orange can displace a volume of water that is greater than or equal to its weight, the orange will float. The peel of the orange helps to displace the water through pockets of air. Removing the peel causes the orange to no longer displace enough water to overcome gravitational force.

This lesson is a beautiful example of buoyancy and an entertaining display of gravitational pull. Gravitational force pulls the orange down while buoyant force pushes it upwards.  Gravity pulls the orange down with a force equal to the weight of the orange.

Children naturally love anything that is water-related, making this simple experiment the perfect opportunity to create an unforgettable interdisciplinary lesson integrating elements of STEAM curriculum and the Montessori environment.