/ materials as nouns
your two examples, Steve, material and materials feature
as part of compound nouns relating to the teaching of a school subject.
It would always be plural in the first example, materials
development, because we are thinking of a range of
materials or of a large project which has many elements.
the second example, it could be singular or plural. We speak of
both teaching material or teaching materials, depending
on how narrowly or broadly we are thinking of them.
we use material in the singular or the plural depends on
the context of use.
we are thinking of equipment or a number of things that you need
for a particular activity, it could be used in the singular, but
would normally be used in the plural:
flat needed a good spring clean so I went out and bought lots
of cleaning materials.
keep all my writing materials in a special compartment
in my briefcase.
material refers to ideas that you can use as a basis for
an article, a book, a play or a film, it is normally used in the
found some useful material for my book on lifestyles in
the Sunday papers.
his latest film, he wrote a good deal of the material himself.
that even when material is used in the singular here, it
has a plural sense.