The Moon cast a shadow on the Earth's surface and covers some parts of the Sun. The proportion of the Sun being blocked depends on the position of the observer on Earth. Depending on the distance of the moon from the Earth, we may ovserve a partial of full solar eclipse from where we are at.
This picture shows that the Sun, the Moon, and the Earth is lined up in a straight line and that is how a Solar Eclipse begins.
What type of Solar Eclipse we can see depends on where we are at when it happened.
The following picture shows the different stages of a Solar Eclipse phenomenon.
If the teacher can prepare and allow the students to watch a Solar Eclipse, it will definitely be an experience of a lifetime.
However, preparations must be conducted before the human eyes can witness the phenomenon, as looking directly into the sun is harmful to the eyes.
A simple glasses as seen below can be made out of cardboard boxes and camera film before presenting to the students.