More than 300 days have passed since public schools in Massachusetts had to close due to the coronavirus pandemic, resorting instead to remote or hybrid learning programs that have proved inferior for many students. Yet, at least in Massachusetts, there isn’t reliable data to assess the stunted progress and outright learning loss that many students have experienced during this time. That’s why the announcement last month that a modified version of the MCAS will be administered this year is welcome. Although the MCAS is typically a graduation requirement for individual students and a way of measuring the performance of districts, it won’t serve either of those purposes this year. Instead, state Commissioner of Education Jeffrey Riley told the Globe the test is needed this year to diagnose any learning deficits. “Right now we are hypothesizing that students learning exclusively remotely are probably going to have more gaps than students who are in-person (full time) or in hybrid learning. We need this data to figure that out,” he said.