Giuliana was a bright seventh grader when we met. She loved science and was curious about everything. I remember wishing her a Happy Solstice early on a December morning and she made a comment about how it was going to get warmer now. I agreed, but added, “Of course it’s going to get colder first since this is the first day of winter.” Giuliana looked at me confused. She tilted her head and said, “But we’re getting closer to the sun now, right?”
“No,” I told her. “We’re not.”
“But isn’t that why we have seasons?”
That’s when I realized that we can’t teach students until we first un-teach some of the misunderstandings they’ve picked up along the way. And a classic misunderstanding that many students believe is that seasons are caused by the changing proximity of the Earth to the sun.
Today’s blog post explains how I teach students the real reason for the seasons.
Why do we have seasons?
The Earth experiences seasons because of its axial tilt and its orbit around the sun. The distance from the sun does not significantly change throughout the year to cause seasons. Instead, it is the tilt of the Earth’s axis—about 23.5 degrees—that plays the crucial role. This tilt causes different parts of the Earth to receive varying amounts of sunlight at different times of the year, resulting in the familiar pattern of seasons.
During the Earth’s orbit, when the Northern Hemisphere is tilted towards the sun, it experiences summer. This means that sunlight hits this hemisphere more directly, causing warmer temperatures and longer days. Simultaneously, the Southern Hemisphere, tilted away from the sun, receives less direct sunlight, leading to winter with cooler temperatures and shorter days. This phenomenon reverses six months later when the Earth is on the opposite side of its orbit.
In spring and autumn, neither hemisphere is tilted directly towards or away from the sun. Instead, both hemispheres receive relatively equal amounts of sunlight. These transitional seasons are characterized by moderate temperatures and roughly equal lengths of day and night. Spring brings gradual warming and new plant growth, while autumn features cooling temperatures and the shedding of leaves from deciduous trees.
How to help students understand seasons
The best way to demonstrate what causes seasons is to use a globe and a flashlight to demonstrate how the tilt of the Earth’s axis affects the distribution of sunlight. This visual aid helps students understand how different areas receive varying amounts of sunlight throughout the year. Do this activity as a demonstration or in small groups and have students compare the amount of light reaching the northern and southern hemispheres throughout one revolution.
One of the best ways to demonstrate the change of the seasons is to graph the amount of daylight at a location throughout the year. Students could research this information or you could provide it to them. One way to do this is to provide students with a link to a spreadsheet that already has the information embedded. 
Then, as they calculate the amount of daylight, the graph is automatically created for them.
Enrich this activity by asking different groups of students to complete the activity for locations at different latitudes.
By explaining that it is the Earth’s axial tilt and its orbit around the sun that cause the seasons, we can help students gain a clearer and more accurate understanding of this fundamental phenomenon.
Through interactive models, graphing daylight hours, and engaging activities, we can make learning the science behind what causes seasons both comprehensible and enjoyable for our students. Whether it’s using a globe and flashlight to demonstrate sunlight distribution or having students create graphs of daylight hours, these hands-on experiences reinforce the concept that it’s the tilt of the Earth’s axis that leads to the seasonal changes we observe.
To further support this learning, consider incorporating seasonal activities into your lessons, such as the color-by-number PDF activity or the interactive slides for virtual learning. These tools provide additional practice and self-checking opportunities, ensuring students grasp key terms like equinox and solstice while seeing the practical application of their knowledge.
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