A second-grade teacher uses flexible grouping and different types of texts for reading groups. What principle of effective reading instruction does this demonstrate?

The choice indicated demonstrates the principle of transitioning students to more challenging texts as they progress in their reading skills. This principle is pivotal in reading instruction, as it helps to match the texts to the students' current levels of understanding while gradually introducing more complex material. Such a strategy not only promotes increased comprehension and critical thinking but also helps build confidence as students continually meet and overcome new challenges in their reading.

In the context of flexible grouping, the teacher can create environments where students are grouped according to their needs and abilities, allowing for appropriately challenging texts that cater to their individual growth. This approach enhances engagement and fosters a sense of achievement, motivating students to further develop their reading capabilities.

The other principles mentioned, while relevant to reading instruction, do not directly align with the demonstration provided in the scenario. They focus more on accommodating diverse backgrounds, aligning with state standards, and exposure to various genres, but the primary focus in this case is on ensuring that students are consistently engaging with increasingly complex texts to support their ongoing development.