Why Arrows Change Direction When Viewed Through a Full Glass of Water

Science teacher Mrs. B (Nancy Bullard) demonstrated how a pair of arrows facing in one direction changed to the opposite direction when viewed through a glass of water. She explained that it is due to the refraction of light as it passes through the water and the curved glass.

No matter how many times I try this, it blows my mind. As I pour water into this glass, the arrows change direction .This is because as the light travels through the water, it refracts. Additionally, the curved glass acts like a lens, which is how your eyes work.