In this unit students will be able to identify sources of light, describe the interaction of light with different materials, and infer the pathway of a light beam.
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Using light and shadow to make puppets-
Sources of Light
Some sources of light are manmade and some are natural.
Natural and artificial light sources:
Natural sources
Artificial
Where do the candles fit?
Let's sort-
Fun Corner
Let's think-
- Is moon a source of light ?
- What about cat's eyes?
Emit or reflect light
Emit means to give off or produce (Ex. Giving off light).Reflect.
Reflect means to give back or bounce (ex. reflecting light).
Reflect means to give back or bounce (ex. reflecting light).
Does light travel in a straight line?
Activity-
Purpose: To discover how light travels .
Materials
Purpose: To discover how light travels .
Materials
- 3 index cards
- small piece of modeling clay or sticky tack
- flashlight
- hole puncher
- ruler
- science journal
- For each index card, use a ruler to draw lines connecting opposite corners of the card.
- At the intersection of the two lines, use a hole puncher to punch a hole in the center of the index cards.
- For each card, use a small piece of modeling clay and place the card into the clay to create a "stand" for the card. Place the cards so that they stand vertically and at an equal distance from each other. See Diagram.
- Place the flashlight at one end of the row of index cards and turn off the light in the room.
- Arrange the index cards so that light can be seen through all the holes.
- Observe and record your observations.
- How can light be seen through all the index cards?
- What does the experiment prove about the path light travels?
- What would happen if the holes were smaller?
Transparent- Translucent- Opaque
Experiment: Does light go through?
Explain the difference between transparent, translucent, and opaque. Please include examples and explain how light rays act in your explanation.
Shadow
What is shadow?
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Have you ever noticed how shadows change? Sometimes they are longer, sometimes they are shorter, and sometimes they seem to disappear! Find out what causes this to happen. You will collect data to find out why your shadow changes throughout the day.
What makes best shadow? Transparent, translucent or opaque? WHY?
Shadow and Reflection
Reflection
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Comparing reflectors
Objectives
• Students predict which types of objects reflect light best and compare the results with the prediction.
• Students recognize that light is reflected better from some surfaces than others.
Materials
For each pair
1 pc. aluminum foil, 4-in × 4-in (crumpled)
1 pc. aluminum foil, 4-in × 4-in (smooth)
1 pc. construction paper, black, 4-in × 4-in
1 fl ashlight with batteries
1 metal spoon
1 mirror, plastic
1 plastic sandwich bag
1 pc. waxed paper, 4-in × 4-in
1 pc. *white paper
1 pc. * white paper, 4-in × 4-in
Step 1:
Predict and sort sort objects into two groups: objects you think are good reflectors and objects you think are bad reflectors. Write your predictions on the Comparing Reflectors page.
Step 2:
Place a piece of white paper on desk and stand the flashlight up on the white paper so that the light shines up at the ceiling. (Darken the room.) Then hold each object about 3 cm above the flashlight. Compare the brightness of the white paper on their desk when each object is held over the flashlight.
Explanation: The more light that is reflected onto the white paper, the better the object is at reflecting light.
Rate each object as an excellent reflector, good reflector, or poor reflector.
Assessment questions: Write answers of following questions in your science journal.
1. Which do you think would reflect more light, a doorknob or a paper plate? Why?
2. What word means to bounce back from a surface?
3. Sort the objects into two piles: good refl ectors and poor refl ectors.
foil, black paper, mirror, plastic sandwich, metal spoon , waxed paper
4 What makes an object a good reflector?
• Students predict which types of objects reflect light best and compare the results with the prediction.
• Students recognize that light is reflected better from some surfaces than others.
Materials
For each pair
1 pc. aluminum foil, 4-in × 4-in (crumpled)
1 pc. aluminum foil, 4-in × 4-in (smooth)
1 pc. construction paper, black, 4-in × 4-in
1 fl ashlight with batteries
1 metal spoon
1 mirror, plastic
1 plastic sandwich bag
1 pc. waxed paper, 4-in × 4-in
1 pc. *white paper
1 pc. * white paper, 4-in × 4-in
Step 1:
Predict and sort sort objects into two groups: objects you think are good reflectors and objects you think are bad reflectors. Write your predictions on the Comparing Reflectors page.
Step 2:
Place a piece of white paper on desk and stand the flashlight up on the white paper so that the light shines up at the ceiling. (Darken the room.) Then hold each object about 3 cm above the flashlight. Compare the brightness of the white paper on their desk when each object is held over the flashlight.
Explanation: The more light that is reflected onto the white paper, the better the object is at reflecting light.
Rate each object as an excellent reflector, good reflector, or poor reflector.
Assessment questions: Write answers of following questions in your science journal.
1. Which do you think would reflect more light, a doorknob or a paper plate? Why?
2. What word means to bounce back from a surface?
3. Sort the objects into two piles: good refl ectors and poor refl ectors.
foil, black paper, mirror, plastic sandwich, metal spoon , waxed paper
4 What makes an object a good reflector?
Why?
Refraction
Light and colour
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How do we see?
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Can the sun damage my eyes?
Why Shouldn't You Look at the Sun? |
Do computers damage my eyes? |
Camera and human eyes
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Let's make a periscope
Light Vocabulary
Light : A form of energy that travels in waves.
Energy: The ability to do work.
Reflect: To bounce back from a surface.
Transparent : Allows most light through.
Translucent : Allows some light through.
Opaque : Does not allow any light through.
Refraction: The bending of light when it moves from one material to another.
Energy: The ability to do work.
Reflect: To bounce back from a surface.
Transparent : Allows most light through.
Translucent : Allows some light through.
Opaque : Does not allow any light through.
Refraction: The bending of light when it moves from one material to another.
Practice and try
cornea - The transparent, curved covering in the front of the eye.
false - T/F White light is made of only one colour.
heat - Light and __________ are related to each other
lens - The ____ is the part of the eye that refracts light to focus it
lense - A transparent material used to bend light
luminous - Objects that can make their own light
nonluminous - Objects that cannot make their own light.
opaque - Does not allow any light rays to pass through.
optic nerve - The part of the eye that sends messages to the brain
pupil - The opening in the iris that allows light to enter the inside of the eye
rays - Straight lines of light
reflection - The bouncing of light off an object
retina - The back part of the eye where an image forms
shadow - A _________________ is a dark shape caused when an object blocks light.
straight - Light travels in a ______________ line
translucent - Allows some, but not all, light rays to pass throught
transparent - Allows all light rays to pass through
T/F
true - The colors we see are the colors that reflect from the objects around us
true - All the colors that make up light are called visible spectrum
true - Lenses are used in eyeglasses, microscopes, magnifying glasses, and telescopes
Practice for test
Final Activity
In a group make a shadow puppet show:
Activity: Shadow box theatre |
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