From January to December, the weather never stands still. It's cold in some months and hot in others. In some months, leaves grow on trees. In other months, leaves fall off trees. It snows, and it rains. Of course, all these changes are parts of the seasons. What makes the difference between winter, spring, summer, and fall?
It's all in how the Earth moves.
The Earth moves around the sun once a year. The Earth also spins around an imaginary line. This line runs through the Earth from the North Pole to the South Pole. It's called the Earth's axis. The Earth makes a full rotation on its axis once a day.