Task 9

Materials and tools for a working group:

glass jar, water vessel, polystyrene balls, crayons

In order to provide pupils with other evidence that the water level remains horizontal, he will use a large, transparent water container, at the level of which the continuous layer of polystyrene balls is used. He takes a glass without lid and shows the pupil what happens if it is immersed upside down into a water container. The task of the pupils is to draw the first row in the table to the verification section where the water level is located or easier – where the polystyrene balls are found. The full vertical immersion of the jar into the water container also shifts the water level in the jar (as the air from the jar cannot escape) together with the polystyrene balls. The objective of the activity is not to explain to the pupil why this happens, the important is to observe what is going on with the water level in the jar if we turn the cup in different ways.

After the initial observation, the teacher can lead the pupils to make predictions about the individual situations in the table in Task 9 as to how the water level will be stored in the container, but also in the glass, in each situation. It is advisable to guide the pupils to color the part of the vessel in which the water is located, as accurately as possible. Then the predictions are verified by dipping the cup under the surface.

At the end of the observation, the teacher leads pupils to generalise observations, which focus on the fact that the water level in the large container and the water level in the glass (jar), which we immersed into the water, is still horizontal. In doing so, the teacher refers to the pupil‘s findings and demonstrates it again on a water container. As in the previous task, the task of pupils in trying to explain in their own words the connection of this observed phenomenon with the gravitational effect of the Earth.