The most common use of suffixes is to denote verb tense or noun plurals. Suffixes are also added to form comparative and superlative adjectives. Another use is to change words from one part of speech to another (i.e., act to actor, verb to noun).
The 18 sets in each of these levels are aimed at building structural knowledge. First students arrange the 10 root words in a column. In small print under each root word, it denotes whether the root is a verb (tense), noun (plural), adjective (comparative or superlative), or part of speech being changed. Students then read the cloze sentences and use context to match root words, suffixes, and sentences. For some words, a prefix must also be added.