What Causes the Change of Seasons?

Content Standards

Students will learn about the relationship between the Earth, Moon, and the Sun, and understand how the tilt of the Earth’s axis and its revolution around the Sun cause the change of seasons.

Performance Standards

Students will be able to:

Explain the role of the Earth’s tilt and revolution in causing seasons.
Differentiate between rotation and revolution of the Earth.
Use 3D XR models to show how Earth’s position affects the length of days and nights, and temperature changes.
Relate the concept of seasons to daily life examples (summer, winter, etc.).

Alignment Standards

Reference: NCERT Grade 7 Science, Chapter 12: Earth, Moon, and the Sun; Section 2– Revolution of The Earth

Learning Objectives

By the end of the lesson, students will be able to:

Define rotation and revolution of Earth.
Explain how the tilt of the Earth’s axis causes different seasons.
Illustrate Earth’s movement around the Sun using a diagram or activity.
Understand why seasons are opposite in the Northern and Southern Hemispheres.

Prerequisites (Prior Knowledge)

Basic structure of the Solar System (Earth, Moon, Sun).
The concept of day and night caused by Earth’s rotation.
Simple idea of Earth’s orbit around the Sun.

Introduction

In this lesson, students will explore how the Earth’s movement around the Sun and its axial tilt cause changes in seasons. Using simple models, visuals, and guided questions, students will connect science concepts with their own experiences of summer, winter, rainy season, and spring.

Timeline (40 Minutes)

Title	Approximate Duration	Procedure	Reference Material
Engage	5	Ask: Why Do Some Places Have Day and Night at the Same Time? Can there be places where day and night happen at the same time? Why? If Earth is always getting sunlight, why is it not always summer everywhere?	Slides
Explore	10	Virtual Lab Let students “see” Earth’s tilted axis revolving around the Sun. Students observe how sunlight falls differently on hemispheres Pause to show June vs. December positions. Guided Question: What do you notice about the part tilted towards the Sun? What happens to the opposite side?	Slides and Virtual Lab
Explain	10	Earth’s Revolution – One year around the Sun = 365 days. Axis Tilt (23.5°) – Fixed tilt leads to unequal sunlight. Direct vs. Slanting Sun Rays – Direct = hotter, Slanting = cooler. Day Length Changes – Longer days in summer, shorter days in winter. Opposite Seasons – North & South Hemispheres experience opposite seasons. Special Dates: June 21: Summer Solstice (North) → longest day. Dec 22: Winter Solstice (North) → shortest day. Mar 21 & Sep 23: Equinoxes → equal day & night. Real-Life Connection: Farmers grow different crops (Kharif in monsoon, Rabi in winter). Festivals like Holi (spring), Diwali (post-harvest), Christmas (winter).	Slides and Virtual Lab
Evaluate	10	Students will attempt the Self Evaluation task on LMS.	Virtual Lab
Extend	5	Scenario-Based Learning: Ask: “How would life be different if Earth’s tilt was greater (e.g., 45°)?” Which is more important for seasons – Earth’s revolution or Earth’s tilt? Why? Research how farmers decide which crops to grow in different seasons.	Slides

What Causes the Change of Seasons?

Introduction

Have you ever wondered why we feel hot in summer, cool in winter, and see leaves fall in autumn? The answer lies in the relationship between Earth, the Sun, and Earth’s tilt. Seasons are not caused by Earth being closer or farther from the Sun, but by the tilt of Earth’s axis as it revolves around the Sun.

Theory

1. Rotation and Revolution

Rotation: Earth spins on its axis once every 24 hours → causes day and night.
Revolution: Earth revolves around the Sun once every 365 days → causes seasons.

2. Tilt of Earth’s Axis

Earth’s axis is tilted at 23.5° from the vertical.
This tilt causes different parts of Earth to receive different amounts of sunlight during the year.

3. How Seasons Occur

When the Northern Hemisphere tilts towards the Sun → it experiences summer (longer days, more sunlight).
At the same time, the Southern Hemisphere tilts away → it experiences winter (shorter days, less sunlight).
After 6 months, the situation reverses.

4. Important Seasonal Events

Summer Solstice (around June 21): Longest day in the Northern Hemisphere.
Winter Solstice (around Dec 21): Shortest day in the Northern Hemisphere.
Equinox (around March 21 & Sept 23): Day and night are equal across Earth.

5. Why Seasons are Not Due to Distance from Sun

Earth’s orbit is slightly elliptical, but the change in distance from the Sun is very small.
Seasons happen because of tilt, not distance.

Vocabulary

Rotation	Earth spins on its axis
Revolution	Movement of Earth around the Sun in 365 days.
Axis	An imaginary line through Earth’s poles around which it rotates.
Tilt	The 23.5° lean of Earth’s axis from vertical.
Solstice	The time when days are longest or shortest.
Equinox	The time when day and night are equal.
Hemisphere	Half of Earth (Northern or Southern).
Orbit	The path Earth follows around the Sun.

What Causes the Change of Seasons?

Introduction

Welcome to the Virtual Lab, an immersive XR experience designed to help students explore how the Earth’s movement around the Sun causes seasonal changes. This interactive simulation demonstrates the role of Earth’s revolution, axial tilt, and varying sunlight distribution in creating different seasons across the Northern and Southern Hemispheres.

Key Features

3D immersive environment showing Earth’s revolution around the Sun.
Interactive controls: Next/Reload buttons for self-paced exploration.
Animations of Earth’s 23.5° tilt and its effect on sunlight distribution.
Seasonal cycle demonstration: March, June, September, and December positions.
Comparative learning: Northern vs Southern Hemisphere seasonal differences.
MCQ Quiz integrated at the end for self-evaluation.

Step-by-Step Procedure for VR Experience

Step 1: Enter the Virtual Lab

Students enter the XR environment where the Earth is shown revolving around the Sun.
An info panel explains: “Earth takes 365 days to complete one revolution around the Sun, and this revolution causes the change of seasons.”.

Step 2: Earth’s Tilt

On clicking Next, the Earth is shown tilted at 23.5°.
Animation demonstrates how different regions receive different amounts of sunlight due to the tilt.

Step 3: Seasonal Demonstration

Clicking Next begins the seasonal cycle with four orbital positions:

March (Spring Equinox)
Sunlight falls equally on both hemispheres → day and night are equal.
June (Summer Solstice in Northern Hemisphere)
The Northern Hemisphere tilts toward the Sun → longer days, shorter nights (summer).
The Southern Hemisphere tilts away from the Sun → shorter days, longer nights (winter).
September (Autumn Equinox)
Sunlight again falls equally on both hemispheres → day and night are equal.
December (Winter Solstice in Northern Hemisphere)
The Northern Hemisphere tilts away from the Sun → shorter days, longer nights (winter).
The Southern Hemisphere tilts toward the Sun → longer days, shorter nights (summer).

Step 4: Evaluation

After interaction, students proceed to the quiz:
- 2 MCQs