If a student is above grade level and answers initial questions correctly, the test will become more challenging as harder test questions are selected to reflect their skill level. If a student is below grade level, poor performance on initial questions will lead the test to provide easier test questions.
In the graph above, we have simulated a reading test for a grade 1 student. Correct answers are in blue. Incorrect answers are in red. You can see how the difficulty of the next test question increases or decreases based on whether the previous answer was correct or incorrect. Initially, there may be large jumps or declines in test question difficulty. Towards the end of the test, the range in difficulty is narrowed as the test better finds the student's learning zone.
This process offers several benefits:
Fewer test questions are required, making for a shorter test.
Students are less frustrated by fewer above-level questions.
Students are not bored by too many below-level questions.
Teachers receive more relevant feedback from meaningful test questions for each student.