6th Grade Science Lesson

The July-December Switch: Why Axial Tilt — Not Distance — Causes Earth's Seasons

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6th GradeClaim-Evidence-ReasoningNGSS MS-ESS1-150 min

Learning Objective

Students will construct a written CER argument explaining how Earth's axial tilt causes opposite seasons in the Northern and Southern Hemispheres by analyzing sunlight angle data, daylight hour graphs, and temperature evidence, while refuting the common misconception that Earth's distance from the Sun causes seasons.

Lesson Overview

Students investigate why New York experiences summer in July while Sydney experiences winter, even though Earth is actually closer to the Sun in January. Using the CER framework, students build an argument that Earth's 23.5° axial tilt — not distance from the Sun — is the true driver of seasonal change.

Materials

CER graphic organizer (one per student)
Sunlight angle vs. temperature data table (printed or projected)
Daylight hours graph for New York and Sydney
Globe and flashlight (one set per group)
Colored pencils (yellow and blue)
Protractor (one per group)
Whiteboard or chart paper for group claims
Exit slip slips (half-sheet)
Projector for anchor image

Scaffolded Task Progression

1Task 1

INITIAL CLAIM — Before looking at any data, make your best guess: What do you think causes Earth to have seasons? Write a one-sentence claim. Choose ONE of the two options below and circle it, then write your claim sentence.

Option A: Seasons are caused by Earth moving CLOSER to or FARTHER from the Sun during its orbit.
Option B: Seasons are caused by Earth's AXIS being TILTED as it orbits the Sun.

My Claim: I claim that seasons are caused by ___________.

2Task 2

CLAIM WITH BASIC SUPPORT — Look at the two images from the anchor phenomenon (New York and Sydney on January 3rd). Write a claim that addresses the July-December Switch. Use the sentence starter:

'I claim that the reason New York is cold and Sydney is hot on the same January day is because...'

Then list ONE piece of evidence from the images or your prior knowledge that supports your claim.

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