In order to determine her student's independent reading level, Mrs. Swanson's best approach would be to -

To assess a student's independent reading level effectively, conducting a reading fluency check is a strong approach. This method focuses on the student's ability to read text accurately, quickly, and with proper expression, which provides insight into their command over reading skills. Fluency is a critical aspect of reading proficiency; it reflects how well a student can access meaning from the text without getting bogged down by decoding issues.

Reading fluency checks often involve timed readings or assessments that measure words per minute, comprehension of the text, and expression. This real-time assessment allows Mrs. Swanson to evaluate the students' current reading capabilities and determine their independent reading level more accurately than other methods.

Other options, such as administering an informal reading inventory, assigning level-specific books, or reviewing past standardized test scores, may provide some useful information, but they do not give as immediate and applicable insight into the current reading fluency and comfort level of each student as a fluency check does. An informal reading inventory might be useful but can be time-consuming, while past standardized test scores may not accurately reflect a student’s current reading abilities, and assigning level-specific books does not assess individual reading levels at all.