Sight words are so called because the word meaning is committed to memory. Therefore, sight words are understood at first glance as opposed to other words that require sounding out or conscious consideration. Sight words include the most commonly used words in the English language, such as conjunctions and pronouns. In fact, a mere 109 words make up 50 percent of the words used in most school texts, many of which are sight words.
Many sight words are not spelled phonetically. For example, "says" and "of" are two sight words that sound entirely different than they are spelled. To properly link the written and spoken versions of such words, children must have the visual of the word committed to memory. Moreover, sight words consist of the most commonly used words in the English language. If children do not comprehend these words fluently, they are likely to get bogged down and confused when reading through long texts.
Students are often required to read quickly in order to complete in-class tests and assignments. The more sight words a child has committed to memory, the quicker he is able to read and understand a text. The need to pause and consider the meaning of common sight words interrupts the fluency of reading, thereby requiring more time and effort to properly comprehend a text. Furthermore, speed reading techniques, such as skimming, require the reader to pick out keywords in the text. Learning sight words allows the reader to efficiently locate keywords and understand their contextual meaning without having to read each sight word individually.
Learning sight words commits them to long-term memory. This is important for students to develop fluent writing abilities, as well as a proper vocabulary. Since sight words are commonly used in the essential construction of a sentence – such as in the case of connecting ideas with conjunctions – learning sight words helps students compose developed, complex sentences to express their ideas. Lacking a proper sight word vocabulary causes the student to compose awkward sentences with improper wording. Furthermore, students are more likely to use words out of context when they have to look up definitions in a dictionary or thesaurus.