# Engineering Water Prisms

In this unit, students focus on the science phenomenon of light energy, investigating how it travels in a straight line and interacts with matter. Students apply their knowledge to design a prototype with mirrors and water that creates rainbows. This page showcases each component of the lesson.

## Science Background for Teachers:

The science background gives teachers more in-depth information about the phenomena students explore in this unit. Below is an excerpt from the science background information for this unit on patterns in light.

Rainbows are caused by light interacting with matter. All light is a form of kinetic energy that travels through space, and like all energy, all light has a source. The sun is the largest source of light on Earth, and its energy travels through space to Earth, providing light and heat.

Light is complex, and there is still much that scientists don’t know about it. There are different models of light that scientists use to better understand how light moves and how it interacts with matter. The two models explored in this unit are the ray model and the wave model.

The ray model describes how light moves in straight-line paths called light rays. Whenever you see a narrow beam of light, it is actually a bundle of many parallel light rays. The ray model is useful for describing how the path of light changes when it interacts with matter.

The wave model is useful because in many instances, light behaves in a similar way to sound waves and other kinds of waves. Both models are useful for describing how light interacts with matter to form rainbows.

We’ll start with the ray model. Light can move for an infinite amount of time and distance in a vacuum, which is space that lacks matter. Whenever a light ray interacts with matter, the light ray changes in some way. When a light ray comes into contact with matter, it can be reflected, refracted, or absorbed.

Reflection occurs when a light ray bounces off of the surface of an object, which happens when it encounters a substance that acts like a barrier, similar to a ball bouncing off of a wall. Almost all objects reflect some light. This is how we see. Light rays reflect off of the object in all directions and into our eyes.

Some materials are more reflective than others. For example, the surface of a mirror is so smooth and reflective that you can see your image in it because the rays of light are reflected off of the smooth surface in the same pattern in which they arrived. With a rougher surface, the light rays are reflected in many directions because the roughness of the surface means that each ray of light hits the surface at a slightly different orientation.

Refraction occurs when a ray of light passes from one medium to another and changes direction. Unlike reflection, the light moves through the second material when it refracts. However, the direction of its path changes.

## Science Lesson: Engineering Water Prisms

In this lesson, students explore how light energy can be reflected, refracted, or absorbed when it interacts with matter. They then apply this knowledge to design a device that uses water and mirrors to create rainbows that shine on a vertical surface.

## Science Big Ideas

• Both sound and light are forms of kinetic energy that can be transferred from one place to another.
• Sound moves in waves of vibrating molecules. It begins at a source and travels outwards until the energy is fully passed on.
• Light travels in a straight line until it comes into contact with matter, at which point it can be absorbed, reflected, or refracted.
• Light can also be understood as a wave, similar to a sound wave. Light waves come in many sizes.

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## Science Essential Questions

• How does sound move from one place to another?
• How is light similar to sound? How is light different from sound?
• How does the path of light change when it is reflected?
• What would happen to our ability to see if light couldn’t reflect off of objects?
• How does the path of light change when it is refracted? How does the path of light change when it is absorbed?
• How are transparent materials different from translucent materials?
• Why can’t people see all of the light waves that exist?
• How do light waves explain why we see different colors?
• How do prisms support the argument that white light is made up of a mixture of different colors?
• Why are rainbows a result of reflection, refraction, and dispersion?

## Common Science Misconceptions

Misconception: White light is colorless and clear.

Fact: White light is made up of a mixture of colors.

Misconception: When white light passes through a prism, the prism adds colors to the light.

Fact: Prisms don’t add colors, but they do add separate visible light into its spectrum of colors.

Misconception: White light allows you to see the “true” color of an object.

Fact: We see colors because of how light is reflected or absorbed by an object.

## Science Vocabulary

Dispersion : the separation of visible light into its different colors

Light : a form of kinetic energy that travels through space

Rainbow :  an arc made up of different colors that forms in the sky when light is reflected, refracted, and dispersed in water droplets

Gravity :  a force of attraction between all matter

Reflection :  occurs when light bounces off of the surface of an object

Refraction : occurs when a ray of light passes from one medium to another but changes direction

White Light :  a mixture of all the colors that make up visible light: red, orange, yellow, green, blue, indigo, and violet

## Lexile(R) Certified Non-Fiction Science Reading (Excerpt)

Can You Fly Over a Rainbow?

In 2014, Melissa Rensen was on a plane. She took a photograph out the window. Later, Melissa looked at her pictures. She saw bands of colors just below the clouds. It looked like the plane was flying over a rainbow.

However, people began to question the photograph. They said it isn’t possible to fly over a rainbow. This is because rainbows are optical illusions. It is impossible to see a rainbow in front of you and to fly over it.

Rainbows are Light

Rainbows are caused by light interacting with matter. All light is a form of kinetic energy that travels through space. The sun is the largest source of light on Earth.

Light is complex. There is still much that scientists don’t know about it. Scientists use different models to better understand how light moves and how it interacts with matter.

One model is a ray model. This model describes how light moves in a straight line. These straight-line paths are called light rays. When you see a narrow beam of light, it is actually a bundle of many light rays. The light rays are parallel. They move in the same direction as each other.

Another model is a wave model. This is because in many instances, light behaves in a similar way to sound waves and other kinds of waves. However, unlike sound waves, light doesn’t need to travel through matter. We’ll use both models to describe how light interacts with matter to form rainbows.

## Hands-on Science Activity

For the hands-on activity, students investigate how light interacts with different materials and then apply what they know about light energy to engineer a device that uses specific materials to create rainbows. This lesson has two parts, an investigation and an engineering challenge. In the investigation, students investigate how light interacts with different materials. In the engineering challenge, students use information from a scenario to define the main problem facing a museum that needs to project a certain spectrum of light on a statue. Students work in teams to come up with possible solutions to solve the problem.

## Science Assessments

KnowAtom incorporates formative and summative assessments designed to make students thinking visible for deeper student-centered learning.

• Vocabulary Check
• Lab Checkpoints
• Concept Check Assessment
• Concept Map Assessment
• And More...

### See How KnowAtom Aligns to NGSS Science Standards

Discover hands-on screens-off core science curriculum for student centered K-8 classrooms. KnowAtom supports classrooms with all hands-on materials, curriculum, and professional development to support mastery of the standards.