Discrepant Event Demonstration
Student Handout
Draw the arrow behind the glass before the water is poured into it.
Draw your PREDICTION for what the arrow will look like when the water is poured into the
glass.
Draw what the arrow ACTUALLY looks like when the water is poured into the glass.
WHY do you think this is?
Here’s why!
The definition of refraction refers to a wave bending when it enters a medium of a
different speed. Light normally travels in a straight path, which is called a ray. When the ray
passes through a transparent material (such as water!) the light will bend.
Light travels through water slower than it does through air, so when the light goes
through the water, it slows down (which makes it change direction), and when it leaves the glass
it speeds up again which causes the arrow to appear as though it has turned.