Concerned that too many students are attempting to learn from home, Governor Charlie Baker on Friday made his biggest push yet for schools to reopen classrooms — even in communities like Boston where coronavirus cases have been surging — issuing a new set of rules that strongly discourages remote learning.

In making the announcement, Baker upended previous state guidance that had urged school districts to shift learning online if coronavirus positivity rates put communities at high risk for widespread transmission. Now, under the new state rules, districts should close schools or classrooms only as a “last resort” — when there is evidence of transmission or in communities where COVID-19 positivity rates are exceptionally high.