Which letter combination should a first-grade teacher introduce first according to systematic phonics instruction?

The best approach to systematic phonics instruction for young learners, such as first graders, is to start with letter combinations that are both frequent and phonetically straightforward. The 'th' combination, which includes sounds that are voiced (as in "the") and voiceless (as in "think"), plays a crucial role in expanding students' phonemic awareness and their ability to decode a wide range of words.

Introducing 'th' can help children identify both sounds in meaningful contexts, as these sounds occur in many common words they will encounter in their reading. This foundational knowledge supports their phonics development and lays the groundwork for reading fluency.

Other combinations such as 'sh,' 'ch,' and 'ph' may also be valuable, but they typically appear less frequently in everyday language. These combinations are also distinct sounds but do not provide the same level of functional vocabulary for early readers as 'th' does. Focusing on 'th' first can thus enhance children's decoding skills and promote confidence in their reading right from the beginning.