This homework assignment has three short sections to it, having students practice definite and indefinite articles.
The first section has students fill in the definite and indefinite articles for feminine, masculine, masculine vowel/h, feminine vowel/h, and then vowel/h plural subjects.
The second section has students practice creating the correct prepositions for nouns in simple sentences. For this, students have to know the difference between using "de" versus "un" or "à".
The third section has students practice using the correct form of "de" according to the context. The tricky part is for them to know whether they need to match "de" to the noun it is representing or not based on whether there is a quantity adverb involved. (For example, you would say "Je mange de la glace" or "Je mange beaucoup de glace".)