One of the things that has been ignored in discussion of the seasons
is that it is a cognitively difficult thing to understand. The
drawings in the book are probably red herrings. While they may
confirm the naive idea that distance is the primary factor, it is very
doubtful that they actually cause the idea. The idea of distance is a
concept that students already bring to the table, and they know that
distance from a hot object changes the amount of heating you
experience. This is the simple natural explanation and as a result it
forms a powerful misconception.
The idea that the angle changes intensity of the sunlight per area is
a 3 variable situation. Accordingly students who are not at the
formal operational level will have extreme difficulty with it. The
video shows a teacher just explaining it. That is also a primary
source of difficulty. By presenting the concept first without the
necessary exploration, the students will not be able to make sense of
it. Remember, the learning cycle must have exploration, term/concept
introduction, application in that precise order. Now the age at which
this is generally done, 10+, is ok because it is possible for students
to be at the formal operational level, but remember that only 20% are
at that level upon HS graduation, and the number is somewhat smaller
at 10+. The development of formal operational thinking takes time, so
the seasons may be better tackled at a later age.
A useful thing would be to have a model of the earth where the
students could observe the amount of light intensity/area. I would
propose a globe with either a light sensor imbedded in it attached to
a meter, or a translucent section that provides light in the interior,
and a peephole that students could observe the light intensity. Then
students could see the effect of the angle. Then they could explore
how the angle and the illumination changes with the seasons.