Thinking about the teaching
By far the most common response to explaining the seasons is in terms of distance from the Sun. This is based on the common-sense reasoning that if you go closer to a glowing source, then you become warmer.
Voice of the street: The Earth is closer to the Sun in the summer, so it must be warmer.
This seems to be a reasonable line of argument, further developed as
Voice of the lane: The closer you are, the warmer it gets.
Unfortunately it's on the wrong track!
The slightly elliptical orbit of the Earth around the Sun means that we (in the Northern Hemisphere) are 152 million km from the Sun in summer but 147 million km from the Sun in winter. The Earth is actually nearer to the Sun in winter!
(And it is only a 3 percent
difference, probably not enough to explain the difference in average temperatures between summer and winter in any case.)
This idea is, unfortunately, supported by those textbooks which show the orbit of the Earth around the Sun as a very obvious and flattened ellipse.
This not an accurate representation. The orbit of the Earth is only slightly elliptical.
One thing you should look out for are those children who accept the idea that seasonal changes are due to the tilt of the Earth but then suggest that the tilt makes one hemisphere closer to the Sun, thereby bringing summer.
This is not correct; it is a projected area effect not a distance effect.
Here is the essence of the argument. There is much more in the Physics Narrative.
There is another line of thinking, that experience suggests you are more likely to come across in adults, but it is worth watching out for.
Wrong Track: The Sun is lower on the horizon in the winter, so there the rays have to travel through a greater thickness of atmosphere, so they are weaker.
As ever, there is some reason for believing this, but the numbers just don't stack up. The Sky does appear more red in the morning and evening because some of the blue fraction of the light is affected by the atmosphere, and is scattered (which is why the sky overhead appears blue). Notice that this is an effect that depends on direction, rather than on thickness.
There is, of course, some absorption of the insolation by each kilometre of atmosphere, but a model of the differences between a summer and winter day do not suggest that there is enough of a difference for it to be a significant factor in accounting for the seasons.
The atmosphere is a variable and complex filter—the quantity of water vapour locally is a big factor—but a justifiable range for the absorption is 5–16 W m -2 / km.