Final answer:
A first-grade teacher looking to maintain flexibility in the composition of intervention groups for decoding skills should use heterogeneous grouping, which allows for diverse skill levels within the same group and accommodates changes in student abilities.
Step-by-step explanation:
To ensure that intervention groups for decoding skills are flexible and not composed of the same students for the entire year, the first-grade teacher should implement C) Heterogeneous grouping. This approach involves mixing students of different abilities and skill levels within the same group, which contrasts with homogeneous or ability grouping where students of similar skills or abilities are grouped together. Heterogeneous grouping allows for greater flexibility as students' skills develop at different rates, and it prevents the static formation of groups based on initial assessments.In the context of education, ability grouping is the term that describes the assignment of students to specific education programs or classes based on various criteria like test scores, previous grades, or perceived ability. It is not the best practice for maintaining flexible group compositions in intervention settings because it can lead to fixed groupings that may not accommodate changes in students' learning progression.