This is one of the three educational interventions with solid evidence of it working. The other two are air conditioning and free school lunches. People don't get excited over them though, because they have nothing to do with teachers or curriculum or educational theory.
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.
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.
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)
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.
