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Basic 3 · Science · Earth Science

Repeating Natural Events

In this topic you will describe events in nature that happen again and again and how long they last.

By the end of these notes you should be able to:

  • Describe day and night as a 24-hour cycle
  • Describe the wet and dry seasons in Ghana
  • Name other repeating events

What you already know

  • Dry and wet seasons (Basic 2)

Copy everything that has a blue line on its left into your notebook. The other parts are for reading.

Strand
Cycles
Sub-strand
Earth Science
Indicator
B3.2.1.1.1 – Describe some cyclic events like day and night wet and dry seasons and their intervals/periods

Introduction

The sun rises every morning. The rains come every year. These events repeat in cycles.

1. Day and Night

One day and one night together take 24 hours.

This happens because the Earth spins once every 24 hours.

2. Seasons in Ghana

Rainy seasons
Part of GhanaRainy seasons
southtwo: a major one (about April to July) and a minor one (about September to November)
northone: about May to October

The rest of the year is the dry season. The harmattan blows in the dry season.

A year calendar showing rainy and dry months for southern and northern Ghana
Figure 1: Seasons in Ghana Draw your own season calendar.Illustration: Sirbus

3. Other Cycles

  • a week: 7 days
  • a year: 12 months
  • the moon's shape changes over about a month

New words

cycle
Events that happen again and again in the same order.
interval
The time between repeated events.
spin
To turn round and round.
harmattan
A dry, dusty wind in the dry season.

Summary

  • Day and night take 24 hours because the Earth spins.
  • Southern Ghana has two rainy seasons; the north has one.
  • Weeks, months and years are also cycles.

Class activity: Cycle Calendar

  1. Look at the calendar.
  2. Shade the rainy months for your area.
  3. Talk about what farmers do in each season.

You need: Locally made clay globe, Printed photographs of Ghana’s wet, Dry seasons, Dried maize cob, Fresh green leaves

Exercises

Answer in your exercise book first, then check your answers.

  1. 1. How many hours are in one day and night?

    • A. 24
    • B. 12
    • C. 7
    • D. 30
    Show answer
    Answer: 24The Earth spins once in 24 hours.

  2. 2. How many rainy seasons does northern Ghana have?

    • A. One
    • B. Two
    • C. Three
    • D. None
    Show answer
    Answer: OneThe north has one rainy season.

  3. 3. Southern Ghana has two rainy seasons.

    • A. True
    • B. False
    Show answer
    Answer: TrueA major and a minor one.

  4. 4. The harmattan blows in the rainy season.

    • A. True
    • B. False
    Show answer
    Answer: FalseIt blows in the dry season.

  5. 5. Events that happen again and again are a ______.

    Show answer
    Answer: cycleThat is a cycle.

  6. 6. Why do we have day and night?

    Show answer
    Answer: Because the Earth spins.The side facing the sun has day.

Homework

  1. Ask a farmer or elder which months they plant crops.