There's also the accidental study of air filters where the outside air quality was not that bad. study https://www.edworkingpapers.com/ai20-188 background https://wfis.org/installing-air-filters-in-classrooms-has-su...

Wow. That paper made no effort to even contemplate whether the improvement was related to reduced particulate matter or to reduced organic gasses. The filters were installed in response to a gas leak — one would imagine they were carbon filters.

Sadly, the literature on the effect of gas concentrations on human intellectual function is incredibly muddy.

Perhaps there is some evidence that people do get excited about free school lunches: Governor Tim Walz’s lunch policy in Minnesota has been a part of the buzz surrounding his recent Vice Presidential nomination.

https://www.cnbc.com/2024/08/19/universal-free-school-lunche...

> free school lunches

What are you referring to?

They're referring to free school lunches. That is, a lunch, at school, which is free. In the sense that it does not have to be paid for on the spot or by the child or family on account. i.e. part of the educational provision itself.

(carefully phrased to avoid "no free lunch" nonsense)

I understand, I meant what solid evidence that it is working and what is meant by that?

It improves educational, health etc outcomes significantly and unlike a lot of proposed interventions in education, it has solid scientific evidence backing it up. Specifically it significantly improves child health (e.g. fewer hospital visits), improves maths and English test scores, lowers the incidence of suspensions of students, and there's no evidence that free school lunch policies increase BMI in those with access to them. For the cost, it is a very effective intervention in improving educational outcomes.

https://www.jandonline.org/article/S2212-2672(23)00301-5/ful...

https://www.brookings.edu/articles/schoolwide-free-meal-prog...

https://onlinelibrary.wiley.com/doi/abs/10.1002/pam.22175