What is progressive difficulty?

First, let's make the distinction between stair stepping of difficulty and equal difficulty as it pertains to reading measures. The measures are individual tests. Tests within a given skill set (reading comprehension, letter names, oral reading fluency, etc.) are of equal difficulty. The stair-stepping of difficulty comes in the progression of skill set administration. The easiest skill sets are the letter names, phoneme segmenting, and letter sounds. Moving up in difficulty are word fluency, passage reading fluency, vocabulary, and the most difficult, reading comprehension.

The first number of a measure indicates the grade. The second number is an arbitrary number and indicates nothing more than a way to distinguish one measure from another. The numbering of the assessments does not represent their degree of difficulty, it’s just a way to keep track of the tests.