Reflexive pronouns are the one pronoun type the Grade 2 standard names outright, and this page covers all seven of them. The word box holds myself, yourself, himself, herself, itself, ourselves and themselves, and there are exactly seven sentences below it, so each word is used once and no more.
That one-to-one fit does the marking. A child who puts “himself” where “herself” belongs finds the leftover word will not fit anywhere else, and the mistake surfaces before the page is finished. Part B matches five ordinary pronouns to their reflexive forms, and the last line asks for one sentence of their own using myself.