5th Grade Amazing Earth February Light 5th Grade Amazing Earth February There is a lot of cool info! Try to keep the presentation fast-moving at 15-20 minutes to allow 30 minutes for stations. Kids love the hands on activities.  Ask students to sit on the carpet so the activities can be set up at their desks. Not everything in notes needs to be reviewed, so make it your own and have fun! You may have to limit questions or the number of students who can answer a question if time runs short.   Ask helpers to: familiarize themselves with the activity and its goal set up during the presentation decide what station/role they are covering rotate stations about every 8-10 minutes Thank you for making Amazing Earth possible!

What is Light? Light is a type of Energy! Buildings People Butterflies Stitches Bacteria Molecules Atoms Nucleus Frequency Wavelength Name Similar sized object This type of energy travels in waves. Since these waves can be all different sizes they are shown on a spectrum. OPTIONAL SAY: We discussed sound waves last month. The place where light exists on the electromagnetic spectrum is different than where sound waves are. (You can see Radio waves on the left side of the photo.) We can only see a small piece of the whole spectrum; the part we see is called Visible Light

Visible Light Light wavelengths are very short, so they are measured in nanometers (nm) We do not usually talk about light by its wave-length number, instead we give them names called Colors

Why do objects have color? Light may be absorbed, reflected, or transmitted (pass through) ASK: why do objects have color? CLICK after student responses. absorbs all the light = black reflects red light & absorbs all others = red reflects all colors equally = white all light passes through = clear The color of an item depends on the color it reflects

How do we describe objects related to light? Transparent: Light passes through. Translucent: Some light will pass through. Opaque: Light can’t pass through the object and will cast a shadow. ASK: who can tell me the words used to describe how much light passes through an object? CLICK after student responses.

Light is amazingly fast! In space, light zips along at 186,000 miles per second Light travels from the sun to Earth - a 93 million mile trip – in about 8 minutes! Very long distances are measured in light years (the distance light can travel in a year = 5,865,696,000,000 miles) As far as we know, nothing is faster than light!

Why is Light extremely important? Our eyes need visible light to see the world around us. Plants use light for photosynthesis; this makes their food, and processes carbon dioxide into oxygen. Light can be converted to electricity to charge batteries or power homes. ASK: what do we need light/sunlight for? CLICK after student responses.

How do we see light? https://www.youtube.com/watch?v=cFVbLnXWn6A This is a 2 min Bill Nye video that explains the structure of the eye and how it processes information to see light. If the video does not project automatically, select the FUNCTION and F8 keys together and then select Duplicate.

Wave Behavior Energy waves, including Light waves, behave in four interesting and useful ways: Reflection – “bounces off things” Refraction – “bends when passing through things” Diffraction Interference these two are weird!

Reflection We see things around us because light “bounces” off them and into our eyes: OPTIONAL: Specular reflection is what happens if you shine a flashlight or laser into a mirror: you get a well­-defined beam of light bouncing back towards you. You will do this during our activities today. Most objects aren't smooth and highly polished: they're quite rough. light hits a rougher surface and bounces off at many different angles, scattering light around it light hits a smooth surface and bounces off at the same angle all together

Refraction This bending and separation effect is called Refraction When light passes through a material it changes speed If it enters at an angle, this change in speed makes the light “bend” Different wavelengths are affected differently, so if many wavelengths are all together they may separate, forming a rainbow, or partial rainbow This bending and separation effect is called Refraction

Diffraction When light waves pass very closely to an object with a sharp edge, this can force part of the wave to change direction This “knife edge” effect forces a new wave front to start and the light appears to “bend” around the corner! Remember that Refraction happens when light passes through an object but Diffraction happens when light passes near an object So what would happen if light waves were passing lots of sharp edges? Diffraction and Interference are not part of SOLs. This is general information to quickly review.

Interference Top wave + Bottom wave = twice as strong! When one wave comes into contact with another they interfere with each other You can add the two waves together to see how strong the resulting wave will be: Constructive interference OPTIONAL EXAMPLES: Picture what happens when two waves or two ripples in the water crash into each other – sometimes they get larger and sometimes they flatten out Another example is when light hits the surface of a CD. The brighter colors experienced constructive interference and the duller experienced destructive. We’ll see this in our experiments today. Diffraction and Interference are not part of SOLs. This is general information to quickly review. Top wave + Bottom wave = no wave at all! Destructive interference

Light Stations DANGEROUS: DO NOT SHINE LASERS & LIGHTS INTO EYES!!! Break students into three groups to rotate every 8-10 minutes through the stations. Updated 1/26/19 Reflection Station Refraction & Color Mixing Station Diffraction/Interference & Optical Illusion Station DANGEROUS: DO NOT SHINE LASERS & LIGHTS INTO EYES!!!