Explain seasons as caused by Earth's axial tilt, using perihelion/aphelion evidence to refute the "distance from the sun" misconception.
A common but incorrect idea is that seasons happen because Earth gets closer to or farther from the Sun. The real cause is Earth's axial tilt of about 23.5 degrees, which stays pointed the same direction in space as Earth orbits. That fixed tilt means each hemisphere spends part of the year angled toward the Sun (more direct sunlight, longer days) and part angled away (less direct sunlight, shorter days).
Here is the evidence against the distance idea: Earth is closest to the Sun (perihelion, about 147 million km) in early January, the middle of Northern Hemisphere winter. Earth is farthest (aphelion, about 152 million km) in early July, the middle of its summer. If distance caused the seasons, winter and summer would be swapped from what we actually experience -- so tilt, not distance, is the real explanation.
Mastery looks like: They explain seasons using Earth's axial tilt and use perihelion/aphelion timing as evidence against the distance misconception.
Common stumbles: Believing Earth is closer to the Sun in summer; forgetting the two hemispheres experience opposite seasons at the same time.