Colours – Basic 6 Basic Technology Lesson Note (Second Term)

Learning Objectives

By the end of the lesson, pupils should be able to:

1. Mention and identify components of light (rainbow)
2. Differentiate between primary and secondary colours
3. Name objects with characteristic natural colours
4. Mix colours practically

Content

Components of Light – The Spectrum

Visible Spectrum: When white light passes through a prism, it separates into seven colours forming a rainbow.

The Seven Colours (in order):

1. Red – Longest wavelength (620-750 nm)
2. Orange – (590-620 nm)
3. Yellow – (570-590 nm)
4. Green – (495-570 nm)
5. Blue – (450-495 nm)
6. Indigo – (425-450 nm)
7. Violet – Shortest wavelength (380-425 nm)

Memory Aid: “Richard Of York Gave Battle In Vain” or “ROY G. BIV”

How Rainbows Form:

1. Sunlight enters water droplets
2. Light refracts (bends) entering droplet
3. Light reflects inside droplet
4. Light refracts again exiting
5. Different wavelengths bend at different angles
6. Creates spectrum of colours

Primary Colours

In Pigment/Paint (Subtractive Model):

• Red
• Yellow
• Blue

Characteristics:

• Cannot be created by mixing other colours
• All other colours come from these three
• Used in painting, printing, art

In Light (Additive Model):

• Red
• Green
• Blue

Used in: Screens (TV, computer, phone), stage lighting

Secondary Colours

Created by mixing two primary colours in equal proportions.

In Pigment/Paint:

1. ORANGE = Red + Yellow
2. GREEN = Yellow + Blue
3. PURPLE/VIOLET = Red + Blue

In Light:

1. Yellow = Red + Green light
2. Cyan = Green + Blue light
3. Magenta = Red + Blue light

Tertiary Colours

Created by mixing primary and secondary colours:

1. Red-Orange
2. Yellow-Orange
3. Yellow-Green
4. Blue-Green (Turquoise)
5. Blue-Violet
6. Red-Violet

The Colour Wheel

Relationships:

• Complementary colours: Opposite on wheel (Red & Green, Blue & Orange, Yellow & Purple)
• Analogous colours: Next to each other (harmonious)
• Warm colours: Red, Orange, Yellow (energetic)
• Cool colours: Blue, Green, Violet (calming)

Natural Colours in Objects

Why Objects Have Colour: Objects absorb some wavelengths and reflect others. The reflected colour is what we see.

Example – Red Apple:

• White light (all colours) hits apple
• Apple absorbs all colours except red
• Red light reflects to our eyes
• We see apple as red

Natural Colours Examples:

Plants:

• Grass/Leaves: Green (chlorophyll)
• Sunflowers: Yellow petals
• Roses: Red, pink, yellow, white
• Violets: Purple

Fruits:

• Bananas: Yellow (when ripe)
• Oranges: Orange
• Apples: Red, green, yellow
• Grapes: Purple, green
• Tomatoes: Red (when ripe)
• Watermelon: Green outside, red inside

Animals:

• Flamingos: Pink (from diet)
• Cardinals: Red
• Peacocks: Blue and green
• Tigers: Orange with black stripes
• Zebras: Black and white
• Parrots: Multiple bright colours

Natural Phenomena:

• Sky: Blue (light scattering)
• Sunset: Orange/Red (light through atmosphere)
• Ocean: Blue (absorbs red light)
• Clouds: White (scatter all light)
• Soil: Brown (organic matter)

Colour Mixing Experiments

Experiment 1: Primary to Secondary (Paint) Materials: Red, yellow, blue paint; palette; paper

1. Mix red + yellow → Creates orange
2. Mix yellow + blue → Creates green
3. Mix blue + red → Creates purple

Experiment 2: Colour Intensity

• Add white to colour → Makes it lighter (tint)
• Add black to colour → Makes it darker (shade)
• Add grey to colour → Makes it duller (tone)

Experiment 3: Spinning Colour Wheel Materials: Cardboard circle, markers, pencil

1. Divide circle into 7 sections
2. Colour with rainbow colours
3. Poke pencil through center
4. Spin rapidly
5. Colours blend to appear white/light grey

Applications of Colour Knowledge:

1. Art and design
2. Psychology (colours affect mood)
3. Safety (warning colours)
4. Nature (camouflage, attraction)
5. Technology (RGB screens)
6. Fashion and decoration