\uD83D\uDCD8 Answer
TPRI is not a norm-referenced instrument, so the stories do not have grade equivalents or percentile ranks. In the early grades, grade-equivalent scores are highly unreliable. Instead, TPRI is criterion referenced. With respect to the stories, this means the phonic elements and story grammar elements increase in difficulty from grade 1 to 2. In grade 2, the vocabulary level also is higher and the sentence structure more complex. It’s unreliable to think in terms of grade equivalents, because a student who reads at the Frustrational Level on Story 1 at the beginning of the year, may read at grade level by the end of the year due to excellent instruction.
For additional information visit:
https://childrenslearninginstitute.org/resources/tpri/