Lesson 12: Light and Shadows
Light travels from sources and reflects from surfaces, making objects visible. This lesson covers transparent, translucent, and opaque materials and how the positions of a light source and object affect a shadow.
Key Ideas
- Light carries energy. It travels in straight lines through a material that is the same throughout, and it can bounce off surfaces.
- Transparent materials let us see clearly through them. Translucent materials let light through but blur the view. Opaque materials block light.
- A shadow forms when an object blocks light. Other light may still reach the shadow, so it is not always completely dark.
- With an object and screen kept still, moving a small light source closer to the object makes its shadow larger.
- As Earth turns, the Sun appears to move across the sky. This changes the length and direction of shadows.
Vocabulary
- Opaque: Blocks light from passing through, like a thick book.
- Transparent: Lets light through so we can see clearly through it, like clear glass.
- Translucent: Lets some light through but blurs what we see, like wax paper.
- Reflection: Light bouncing off a surface.
- Shadow: A dark area formed when an opaque object blocks light from reaching a surface.
Discussion Questions
- If light travels in straight lines through a uniform material, how do reflections help a lamp light up an entire room?
- If the sun suddenly went dark, how long do you think we would still be able to see the moon? What would eventually happen?
- Why do shadows sometimes have sharp edges and other times have soft, blurry edges?
Supplies
- A flashlight
- A small solid opaque object (eraser, small toy, or block)
- White paper or a light-colored wall