But CO's Atty General, Phil Weiser, who is a candidate to replace Gov. Polis, announced yesterday that if elected he would opt the state out of the voucher plan. So the state's eventual participation is unclear.

In fact, Colorado's Gov. Polis appears to be the first D governor to announce that he will opt in to voucher program, without waiting to see of Trump's Treasury Dept allows states the flexibility to design programs for their states that reflect each state's goals and values.

I believe the HQT provision was not enforced, right? Or maybe the waivers didn't start immediately? But your point/question is a good one. If time on task increased opportunities to learn (which it should, notwithstanding the reading results), how much of this was just a shift in OTL from X to math?

A second possible (likely?) reason is that the state-test-focused instructional time on reading was so superficial and unengaging that it didn't actually improve students' reading skills. If so, that's a devastating indictment of the NCLB era.

Another thread hinted at, that @mattbarnum.bsky.social might pull on, concerns the reading results. Obviously, schools also increased reading-specific instructional time. One reason for no clear NAEP improvements is, of course, that reading scores are less sensitive to school-level changes. But ...

Agreed.
It would also be helpful to expressly connect the dots. The uptick in NAEP math scores likely followed from increased time on math instruction, which was at the expense of other subjects. Even setting aside the other collateral damage, that's a trade-off that many parents do not support.

"Faculty meeting"

Thank you, Heidi. And thanks for sharing this important scholarship.

Very true. This is what we've seen in states with tax-credit voucher programs that include a public-school component (in, e.g., AZ). People with the wealth to do so donate in their own (wealthy) communities.