Students find their ratio from dividing the distance they moved the paper from the index card by the size of the little sunlight spot. Try holding a pencil out at arm's length towards the full moon. The pencil width should just wink out all of the moon's face. If you ask students what a particular season means to them, they'll probably mention the weather usually associated with it. Summer is hot.
Winter is cold.
Spring and Fall are in between. This model, of course, is inconsistent with the fact that while the Northern Hemisphere has summer, the Southern Hemisphere has winter. Furthermore, while it is summer for the Northern Hemisphere, the Earth is actually slightly farther away from the Sun than during the Northern Hemisphere winter. During the Northern Hemisphere's summer, the North Pole is tilted towards the Sun. During the winter, it is tilted away.