Seasons
Seasons is the way Earth's tilt makes sunlight stronger or weaker at different times of year.
Think of it this way
Hold a flashlight above a flat tray at a steep angle. The beam hits a small, bright spot — that is summer. Now tilt the flashlight to a low angle. The beam spreads out over the tray, so each part gets less light and heat — that is winter.
Explaining seasons by grade level
Earth does not sit straight up. It leans to one side. When your part of Earth tilts toward the sun, light hits more directly and it feels warm. When it tilts away, light spreads out and it feels cold.