I’ve just found a great infographic for you. Show it to your student and he/she won’t have any more problems with adjectives.
An adjective is a word that describes a person, place, or thing (nouns and pronouns), and they generally appear before the word they modify. The articles “a,” “an” and “the” are also adjectives.

[Infographic provided by Grammar.net]
2012.01.21 / 21:13 — Lilla Udvarhelyi