The Shadow Illusion

Description:  Derek Muller from Veritasium uses the shadow illusion to show that the size and shape of a pinhole does not affect the image projected. Most of the participants believe they are looking at the shape of the hole rather than the shape of the Sun projected on the wall. This could be an excellent phenomenon to start a unit on light or vision.

Web Resource: Pinhole camera - Wikipedia

Why is Space Black?

Description:  This phenomenon can be used in elementary to explain darkness and illumination. Even though light travels between the Sun and the Earth space appears black because there is nothing (e.g. gas, dust, etc.) for the light to reflect off of. This can also be used as a much deeper phenomenon. Since space is filled with billions and billions of stars and each of them give off light why isn't space completely light? The answer lies in the expansion of the Universe.

Web Resource: Ask Ethan: Why does space appear black?

Vantablack - The Darkest Material on Earth

Description:  Vantablack is an synthetic material created by Surrey Nanosystems. It consists of a series of carbon nanotubes that are aligned vertically. It absorbs nearly 100% of the light that enters the tube giving. Since nearly all of the light is absorbed by the material it appears black. In the video below a bronze statue is covered in Vantablack and it disappears from view. This phenomenon can be used to illustrate the idea of illumination. Even though a light source is present none of the light reflects back to the viewer and so all that remains is darkness.

Web Resources: Vantablack | Surrey NanoSystems , Vantablack - Wikipedia