According to Reading Rockets, the ability to correctly sound out unfamiliar words is the most important skill for a successful reader and the skill that presents the most trouble for struggling readers. Because of this, it's helpful to spend a significant amount of reading workshop time teaching letter-sound correspondences. If your students are grouped by need during reading workshop time, work on more basic letter-sound relationships with struggling students and vowels and blends with more advanced students.
To become confident readers, first-graders need to practice sounding out words using the letter-sound relationships they've learned. During your reading workshop time, introduce or review a letter-sound relationship and then have students practice sounding out several words that feature those sounds. Give feedback as students practice sounding out words, then have them read an engaging short passage or story that fits the pattern they're studying. Adjust these sounds and stories according to the needs of each group of students.
Comprehension is the process of making meaning from reading. Reading without comprehension is just reciting words. To build comprehension, prepare students by asking questions before they read. Connect what they are about to read to something they know. Have students look at any pictures and predict what they're going to read about. Encourage students to look for meaning as they read and have them draw, write or talk about what they learn after reading.
Reading workshops are a time for individual assessment. Because you're working with a smaller group of students, make note of which students are progressing well and which need additional support. When you introduce a new letter-sound relationship, make note of which students read those words successfully and move them on to the next concept. That way, you know which students are still struggling with which combinations. This allows you to target instruction to the students who need it most.