To get right to it: That’s wrong. More importantly it’s also counterproductive if we want to pay teachers more (or get people to take education policy seriously or be able to take a serious stand on using evidence or….you get the idea). We do have a teacher compensation problem, yes, but it’s a lot more complicated than political rhetoric, and especially political rhetoric in 280 characters.
Why is it wrong? Well for starters second jobs are a good talking point but a fractional issue in practice. Less than one in five teachers taking a second job during the school year and one in three in the summer is not “most.” It’s also not a huge source of income. It’s actually more common among private school teachers. The seasonal patterns and patterns among different teachers might not be what you’d expect either.
More fundamentally, the very EPI analysis this rests on (which is funded by the teachers unions it should be noted) places the salary differential at 14% when you factor in benefits – defined benefit pensions, which are deferred compensation, being a crucial part of that although health care costs are also an issue. Still real, but not quite as compelling a tweet. But this part of compensation is a key part of this whole issue (another key part is overall numbers of teachers, more on that below). It’s a significant part of why in many places public dollars for overall teacher compensation continue to steadily climb but teachers are not seeing this in their paychecks every month. You can’t wish this part of the issue away or ignore it.