1. Grade 10-12
2. Grade 4
3. Grade 5
4. Grade 8
5. Source of light
6. Behavior of light
   1. Reflection
   2. Refraction
7. Light
8. Benefit of light
9. SOUND
10. Source of sound
11. High-Low Pitched
12. Noise polution
13. High-Low Volume
14. Behavior of light
    1. Reflection
    2. Refraction
15. The effect of light on life
16. Visible light
17. LIGHT
18. performance
19. mirror
20. glasses
21. optical instrument
22. The obsorption of light
23. photograph
24. Waves
    1. wavelength (λ)
    2. Standing wave
    3. Behavior of light
       1. Reflection
       2. Refraction
       3. Interference
       4. Diffraction
    4. frequency (f)
25. Light
26. Sound
    1. Behavior of Sound
       1. Reflection
       2. Refraction
       3. Interference
       4. Diffraction
    2. Source of sound
    3. Itensity
    4. Sound intensity
    5. Beats
    6. Resonance
    7. Noise polution
    8. Sound quality
27. Electromagnetic waves
28. Benefit of Electromagnetic waves
29. Spectrum
30. fiber optic
31. Light