For teachers making important instructional decisions, and when student responsiveness to instruction is of key importance for educational decision-making, relying on the measure in which slope is more clearly related to overall outcomes may be paramount.
There are two "is"s in this sentence, and I don't know what the "subjects" are in here.
Thanks!
This is a pretty complex sentence, so I'll break it down into parts and put it back together.
The core of this sentence (Main Subject + Main Predicate) is:
Relying on the measure... may be paramount. (paramount = most important)
Measure? What measure? According to the sentence, the "measure" is the correlation between "slope" and "outcome."
Relying on the measure (in which slope is more clearly related to overall outcomes) may be paramount.
So this "is" is part of a dependent clause ("in which...outcomes") that describes "measure." Within this clause, "slope" is the subject, but it is not the subject of the whole sentence.
But this measure is not always the most important - it's only the most important when student responsiveness is also important.
(When student responsiveness to instruction is of key importance for educational decision-making,) relying on the measure (in which slope is more clearly related to overall outcomes) may be paramount.
So the other "is" is part of an adverbial clause modifying the whole sentence, telling when this sentence is true. Within this clause, "student responsiveness" is the subject, but again, it is not the subject of the whole sentence.
Finally, we have a prepositional phrase that tells us who this sentence applies to. It tells us: relying on this measure may be the most important thing for teachers who are making instructional decisions.
For teachers making important instructional decisions, and when student responsiveness to instruction is of key importance for educational decision-making, relying on the measure in which slope is more clearly related to overall outcomes may be paramount.
I hope you find this helpful!
