SCIENCE - Energy, Light and Sound (Lesson 2)

 FOCUS QUESTION

How does light behave?

SPECIFIC OBJS.

1. Investigate the properties of light

2. Investigate the properties of light with materials that are shiny, dull, transparent, translucent and       opaque.

3. Value individual effort and team work

CONTENT SUMMARY

Light is a form of energy. It is detected by the eyes and it enables vision. Light behaves differently when it comes in contact with different types of materials. All objects are either transparent, opaque or translucent. Some objects emit light or reflect light, that is, they are luminous or non-luminous. Luminous objects produce their own light. Non luminous objects reflect light from luminous sources.

PROPERTIES OF LIGHT include:

ü  Light travels in a straight line from a source.

ü  Light travels fast

ü  Light has a dual nature

ü  Light can vary in intensity

ü  Light interacts with matter

ü  Light is comprised of many colours

Light carries energy and information

ENGAGE

Let's  review  the past lesson on luminous and non luminous objects. 

What are they?  Can you provide examples of  each.

EXPLORE

Examine the set of materials which I have placed on your desks. Discuss their appearance, what they are made of. (Mirror, match box, spoon, plastic paper, foil paper, clear class).  I need you to shine your light source on each of the objects and record what happens by ticking the appropriate column on the table below.

OBJECTS	All light went through	Some light went through	Shadow formed	Light is reflected/bounces off
Clear plastic
Mirror
Match box

[Students will discuss why they believe all the materials did not react to light the same way. Then make concluding statements.]

EXPLAIN

Provide concluding sentences about light and how it behaves when it comes in contact with different materials.

EXTEND/ELABORATE

In groups, I want you to use some old CDs to do an experiment. Line up all the holes in the CDs one behind the other. Place them at ales 5 cm apart. Use a wall as your background. Shine the light source at the first hole of the first CD. Explain what happens.

Move the third CD out of place and repeat the procedure. Explain what happens.

(NB cardboard can be used)

In the same groups, use a straw to look at an object, then bend the straw at a slight angle(less than 45 degrees) and check whether the object can still be seen. Record your observation, and explain why the object was/was not seen.

What conclusion can you draw?

Students I want you to watch the youtube videos below to glean additional information on the behavior of light with different objects.

You are required to prepare a Graphic Organizer to capture information learnt on the behaviour of light. Make your notes.

Video: How does light travel?

Video: Science, Light, reflection

Video: Light properties

EVALUATE 

1.   Mrs. King, the grade six teacher, asked Sharla and Amora to examine the picture below, then tell if the light source came from direction A or B.  Amora’s response was direction A, while Sharla’s response was direction B.

Direction A                           Direction B

i    Whose response was correct? 

ii   Justify your answer. _____________________________________

2. List at least two (2) properties of light.

3. Which of the following would not be considered as good reflectors of light?

     

A lump of clay,     spoon,        a piece of mirror,    a book,          a box,         foil paper

 4. Answer true or false for the statements below

Statements	True	False
Light interacts with all materials the same way
Light travels in a straight line
The bounce of light is called reflection
Glossy and shiny materials are more likely to reflect light.
Not all opaque objects will cast shadow if they come in contact with a light source.

 5. Henry performed the experiment below in his Science class. What was he trying to prove?

     

 (a) how light reflects

 (b) how light travels

 (c) how light refracts

 (d) how light shines

6. What is being tested below?

    

(a) how sound travels through different medium

(b) how light travels through different medium

(c) what are luminous and non-luminous objects

(d) how light refracts

7.

8. 

9.Use the diagram below to answer the question that follows.

                OVERHEAD VIEW OF A ROOM

If a person was standing at position P, which two statements would most likely be true if the person was unable to see the sofa?

(a)    Light only travels in s straight line.

(b)   The light from the television was too bright.

(c)    The sofa did not reflect light to the person’s eye.

(d)   There was not enough light in the room.

(e)   The sofa was too far.

10. Define the following:

(a)    Reflection

(b)   Opaque

(c)    Transparent

(d)   Shadow