When should Beginning Blends be introduced to a newcomer? Most instructors wait until students have a grasp of consonant sounds and short vowel CVC words. Whether you choose to teach digraphs or blends first is a professional choice. 'Th' is the most frequent beginning digraph and 'st-' is the most frequent blend in English. In reality, newcomers encounter a combination of beginning and ending consonant clusters throughout their day.
Beginning blends are two or more letters which frequently occur together at the beginning of a word, but maintain their individual sounds. bl- = /b/ + /l/ Beginning blends are usually grouped into three groups: L Blends, R Blends, and S Blends. Most native English teachers choose to teach L blends first. This choice is often based on alphabetic order or their childhood experience. In most situations, I would recommend teaching newcomers the S Blends first. This is a good choice if you teach a class of mixed language learners or they struggle with /l/ or /r/ sounds. However, if you teach a language group who have difficulty pronouncing the /s/ sound, begin the L or R Blends.
One blend which is often mistakenly grouped with digraphs is qu-. Qu- blends the sounds of k and w: qu- = /k/ + /w/. Many native English speakers think of qu- as one sound rather than a blend of two sounds.
There are also three-letter beginning blends. The most common three-letter blend is thr-. Newcomers encounter this blend as soon as they learn to count to three in English. Three-letter blends can produce two or three sound combinations. Two-sound combinations will contain one digraph and one consonant such as shr- = /sh/ + /r/. Spr- = /s/ + /p/ + /r/ is an example of a 3-sound combination.
Why are blends important to learn? Learning blends help newcomers pronounce and spell new words. Blends are one type of "chunk" in English used to form words. They usually stick together when dividing syllables. Knowing blends is one of the many tools needed for decoding new words.