Meaning of "be scaled"

Hi~ What could be the meaning of the words "be scaled" in this context?

If you have any guesses, please comment some here.

It would be a big help for me. Thank you~

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The failure of these choice reforms to catch fire and spread suggests
their limitations. It is irrefutable that for the foreseeable future, the overwhelming
majority of our students will be served by mainstream public
schools where choice and innovation are urgently needed. The choice
movement has put constructive, competitive pressure on mainstream
schools to embrace a wide range of reforms and compete for students. In
addition, the charter movement, at least here in Massachusetts, has produced
some exemplary, innovative, and highly successful school models
that hold promise even if they are only starting to be scaled.

Choice will continue to be an essential companion strategy for the
reform of public education. Choice options will likely grow incrementally,
and experimentation with new hybrid forms of school governance and
service delivery can and should continue. Experiments like the recent
state receivership of the Lawrence Public Schools show great promise.
Efforts to scale choice successes will be watched closely, and positive
results should be embraced. However, choice is not a silver bullet; it is a
mechanism for distributing services rather than a prescription for providing
students what they need to achieve proficiency.
Choice provides autonomy, but autonomy does not