Sight words are any words that we decode quickly and effortlessly. Sight words are not just words like to, from, the, and is; they can also be words like majestic, subtropical, and encyclopedia. We can typically read these familiar words in less than 0.20 seconds, or 200 milliseconds, without any conscious effort. This effortless retrieval of words allows literate adults to read 300 words a minute, faster than we can comprehend speech (Farrall, 2018).

Many high-frequency words contain spelling patterns that students have not yet learned or cannot fully explain using their current phonics knowledge. Words such as said, was, come, and does often create challenges because parts of the words do not match what students expect based on previously taught phonics patterns.

For years, these words were often taught through memorization. Students might repeatedly read, write, and practice the words in hopes of remembering them. However, research suggests that skilled readers do not rely on visual memorization alone to recognize words automatically.

Instead, students learn words most efficiently when they connect sounds, spellings, and meaning through a process known as orthographic mapping.

You may have noticed we’ve used the term “sight word” differently from how it is used in many classrooms. Many educators use the terms “sight words” and “high-frequency words” interchangeably. In this series, we will be careful to differentiate between these two terms, so let’s start with a few key definitions:

The ultimate goal of orthographic mapping is not simply learning individual words. The goal is building a robust orthographic lexicon.

The orthographic lexicon is a reader's mental storehouse of written words that can be recognized instantly and automatically. Some researchers also refer to this as a reader's sight word memory. When a word has been successfully mapped and stored in the orthographic lexicon, the reader no longer needs to consciously decode it. Instead, the word is recognized immediately.

For example, skilled readers typically do not stop to sound out words such as said, people, or because. These words have already been mapped and stored in memory.

As students engage in phonemic awareness, phonics, decoding, spelling, and reading practice, their orthographic lexicon continues to grow. The larger a student's orthographic lexicon becomes, the more efficient and automatic reading becomes.

Heart Words provide a practical way to teach high-frequency words that contain irregular or unexpected spelling patterns. Rather than asking students to memorize an entire word visually, Heart Word instruction helps students identify the parts of the word that can be decoded and the parts that need to be learned "by heart."

For example, in the word said, students can connect the sounds /s/ and /d/ to the letters s and d. The vowel pattern may be less familiar and becomes the part that requires additional attention.

This approach aligns with orthographic mapping because students are still analyzing sounds, letters, and meaning rather than relying solely on memorization. Over time, repeated practice helps the word become stored in the orthographic lexicon, where it can be recognized automatically.

Heart Words can be categorized into two groups – Regularly Spelled and Irregularly Spelled.

• What Are Regularly Spelled Heart Words? Words that can be decoded using common phonics knowledge and letter-sound relationships (decodable words). These are words like and, it, in, and but. Notice that in each of these words, the consonant and vowel letters make the sounds that we expect. We can call these regularly spelled high-frequency words Simple Heart Words.
• What Are Irregularly Spelled Heart Words? Words that deviate from common phonics patterns or familiar letter-sound relationships (non-decodable words). These are words like from, what, give, and do. Each of these words has at least one letter that spells a sound we do not typically expect it to spell. When words are irregularly spelled, research suggests that they are harder to anchor into our sight word memory. Let’s call these Tricky Heart Words.

When educators understand the relationship between orthographic mapping, Heart Words, and the orthographic lexicon, teaching sight words becomes much more intentional. The goal is not to help students temporarily remember a list of words. The goal is to help students build a growing collection of words that can be recognized instantly and effortlessly.

As the orthographic lexicon expands, students become more accurate, more fluent, and better able to focus on comprehension. This is what allows readers to move from laborious word reading to automatic word recognition and skilled reading.