Eric Hanushek eviscerates the union's self-serving push for legislation to reduce class sizes. While smaller classes, at first glance, appear to be like motherhood and apple pie – who could be opposed? – in fact, they are hugely expensive and appear to make little impact on student learning (especially given the cost). The key (discussed below) is teacher QUALITY.

It's like the bad penny that keeps appearing, only it costs hundreds of millions of dollars. The city teachers union has begun pushing a new property-tax proposal tied to a union employment program.

Everyone would be better off if they just stuck to teaching kids.

The union's proposal, announced with great fanfare by United Federation of Teachers boss Michael Mulgrew, is to increase property-tax receipts by placing an added burden on housing owners who do not use their city apartment as their primary residence. The revenues, which they estimate would add up to some $900 million annually, would be used to fund a new low cap on class sizes in grades K-3.

The idea is getting Albany legislators to lower current class size restrictions, which are built into the union-negotiated contract — that is, using the Legislature to force new teacher hiring.

Of course, the unions do not have strong opinions on the specific tax used. Any tax will do, as long as it can funnel money into labor's coffers. So instead of focusing on the levy itself, it is more useful to focus on the true objectives: lowering class sizes in order to hire many new (dues-paying) educators.

This is an idea whose time came, and went, many years ago. In the decade and a half that has passed since the beginning of the class-size-reduction craze, virtually everybody concerned with student achievement has come to realize that further reductions are not a wise way to spend school money.

Support can be tracked back to a single experiment in the mid-1980s, Project STAR in Tennessee. While this was a poorly implemented experiment, it showed some achievement gains in small kindergartens.

Nobody has wanted to repeat that experiment for fear of a different answer. Nationwide, pupil-teacher ratios for the country fell from 17.8 in 1995 to 15.8 in 2008. With the recession, they rose back to 16.4 in 2010 — but this simply reflected the fact that this was the least harmful way to deal with the budget shortfalls. For New York City, the equivalent 2010 number is 14.5. (Class-size numbers are typically higher than pupil-to-teacher ratios, but that's a subject for another day.)

Nobody has shown that the substantial class-size reductions of the past 15 years have paid off in terms of student achievement. Instead, the two main effects of past class-size reduction have been more teachers and more expensive schools.

Worse yet, class size mandates may even HARM poor children because they lead to the sudden hiring of a lot of new teachers, many of whom are inexperienced or bottom of the barrel – and, of course, guess which kids get these teachers? For more on this, see pages 200-202 in my school reform presentation (which is always posted at:http://www.arightdenied.org/presentation-slides). Here's page 202: