Both decoding and encoding skills are needed to build a foundation in reading. Decoding is the process of translating written speech into verbal speech sounds by applying knowledge of letter-sound correspondences. It is the ability to recognize letters, apply their associated sounds, and blend sounds to form words. Encoding is the process of using letter-sound knowledge to write or spell words. Students must understand the various spelling patterns and rules of the Spanish language to correctly construct words in their written products. It is important that students demonstrate their knowledge by applying these rules consistently instead of using invented spelling because they may unknowingly write a real word they did not intend, causing reader confusion.

Students should be able to use their knowledge of hiatuses to correctly spell words that include them. Students should know that there are two types of hiatuses. Formal hiatuses are composed of two strong vowels (a, e, o). The following are examples of words with formal hiatuses, cooperar, tarea, or poeta. Accented hiatuses are composed of a strong and a weak vowel (i, u). The following words have accented hiatuses, corría, proteína, reúno. When a word with a hiatus (formal or accented) is divided into syllables, the vowels that make the hiatus are never in the same syllable: co-o-pe-rar, ta-re-a, co-rrí-a, pro-te-ína, re-ú-no.

Students should be able to use their knowledge of diphthongs to correctly spell words that include them. Students should know that a diphthong is a combination of a strong vowel (a, e, o) and a weak vowel (i, u) in the same syllable. In most cases, diphthongs are not accented, like in the words vai-ni-lla, Eu-ge-nio, boi-na. However, some diphthongs are spelled with an orthographic (or written) accent, like in des-pués, in-ten-ción, or a-vión.