Why Do We Have Seasons? Axial Tilt, Sunlight Angles, and the Earth-Sun-Moon System

Shared by A STEM Educator

6th Grade5e-learning-cycleMS-ESS1-1, MS-ESS1-245 min

Learning Objective

Students will be able to explain that Earth's seasons result from axial tilt causing changes in the angle and duration of sunlight received at different latitudes, and will distinguish this from the common misconception that Earth's distance from the Sun drives seasonal temperature change.

Lesson Overview

Students investigate how Earth's 23.5° axial tilt — not its distance from the Sun — causes seasons by exploring how the angle of incoming sunlight affects energy concentration on Earth's surface. Real-world connections to solar panel optimization and agricultural planning anchor the learning.

Materials

Foam globe (one per group of 3–4 students) with axis marked at 23.5°
Bright flashlight or small LED lamp (one per group)
Protractor (one per group)
Graph paper (one sheet per student)
Ruler (one per group)
Dark construction paper (one sheet per group, for shadow/spread tracing)
Colored pencils (red and blue)
Printed lab recording sheet (one per student)
Whiteboard markers and personal whiteboards or blank paper for VNPS
Tape measure or meter stick
Solar irradiance calculation worksheet (Elaborate phase)
Exit slip cards (pre-printed, one per student)

Scaffolded Task Progression

1Task 1

Look at the two flashlight diagrams your teacher demonstrated. The flashlight's brightness (total energy output) did NOT change between the two positions. In your own words, explain why the tilted flashlight appears dimmer on the paper even though it is equally bright.

[ Interactive graph / diagram — available in the full lesson ]

2Task 2

Using your foam globe and flashlight, model the June Solstice by tilting the North Pole toward the 'Sun' (flashlight). Record your observations in the table below, then answer: Which hemisphere receives more direct sunlight? Which is experiencing summer? How does the angle of light on the Northern Hemisphere compare to the Southern Hemisphere?

Position	Hemisphere with More Direct Light	Season in N. Hemisphere	Season in S. Hemisphere
June Solstice (N. Pole toward Sun)	?	?	?
December Solstice (N. Pole away from Sun)	?	?	?

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