Air: Meaning, Uses & Gases in Air – Basic 2 Basic Science Lesson Note (Third Term)

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

• say meaning of air
• identify the gases in air
• demonstrate the existence of air in nature
• explain the uses of air

Lesson Content:

Meaning of Air: Air is the invisible mixture of gases that surrounds us everywhere on Earth. We cannot see air, but we can feel it and we need it to live.

What Air Contains:

Main Gases in Air:

• Nitrogen (78%): Most of the air, helps plants grow
• Oxygen (21%): We need this to breathe and live
• Carbon dioxide (0.04%): Plants need this to make food
• Other gases: Very small amounts of other gases

Simple Understanding:

• Oxygen: The part we breathe in to stay alive
• Nitrogen: Most of air, helps keep oxygen balanced
• Carbon dioxide: What we breathe out, plants use it
• Water vapor: Tiny drops of water in air

Demonstrating the Existence of Air:

Experiment 1: Air Takes Up Space Materials: Clear glass, paper tissue, bowl of water Steps:

1. Stuff tissue paper in bottom of glass
2. Turn glass upside down
3. Push straight down into water
4. Pull out and check tissue – it stays dry!
5. Why: Air in glass prevents water from entering

Experiment 2: Air Has Weight Materials: Two balloons, coat hanger or stick Steps:

1. Blow up one balloon, leave other empty
2. Tie both to ends of stick
3. Hold stick in middle
4. Blown balloon hangs lower
5. Why: Air in balloon makes it heavier

Experiment 3: Moving Air Materials: Paper, fan or your hand Steps:

1. Hold piece of paper
2. Wave hand or fan near it
3. Paper moves
4. Why: Moving air pushes the paper

Uses of Air:

For Living Things:

• Breathing: All animals need oxygen from air to live
• Plant growth: Plants use carbon dioxide to make food
• Photosynthesis: Plants give us oxygen back
• Bird flight: Birds use air currents to fly

For Humans:

• Respiration: We breathe oxygen, exhale carbon dioxide
• Speaking: We use air to make sounds and talk
• Exercise: More active we are, more air we need
• Cooking: Fire needs oxygen from air to burn

For Transportation:

• Airplanes: Use air to fly in sky
• Hot air balloons: Heated air lifts balloon up
• Sailboats: Wind pushes boats across water
• Windmills: Wind turns blades to make electricity