The claim "Teacher's Unions do not help kids" receives mixed results according to the scholarly source titled 'Teachers Unions and Student Performance: Help or Hindrance?' by Randall W. Eberts. In this study, Eberts explores the role of teachers' unions in public education and how unions affect student achievement. Eberts' study concludes that "The effect of unions on student performance is mixed. Students of average ability who attend school in union districts perform better on standardized tests, whereas low-achieving and high-achieving students perform worse. However, the overall gain in achievement does not make up for the higher cost" ('Teachers Unions and Student Performance: Help or Hindrance?').
Furthermore, Eberts' study suggests "What is the evidence on student achievement? The evidence that is available is not ideal. One would like to assign students randomly to schools that are also randomly assigned to union or nonunion status and then observe student achievement over time. The best approximations to this ideal experiment use extensive statistical controls for both student and school attributes, as well as for the nonrandom assignment of students and schools. But even good approximations to the ideal have been difficult to achieve." ('Teachers Unions and Student Performance: Help or Hindrance?').
It is overall concluded that "The evidence on how unions affect student achievement leads to the general conclusion that there is no simple answer and that generalization is difficult. The average-achieving student does not appear to be harmed by attending union schools and may even fare slightly better, whereas low-achieving, at-risk students and high-achieving students tend to do better in nonunion schools. ('Teachers Unions and Student Performance: Help or Hindrance?').
In consideration of the author of the article and a reliable source that provides research conducted by Eberts on this specific topic - this claim can't be true or false, however, seems to be leaning more towards being false, as research shows that unions do not seem to be harmful to students, and may even fare slightly better, which works against the claim. While Randi Weingarten's claim of 'teachers unions are positively associated with student achievement' may be misleading as she makes it seem there is a lot of research to back up the positive association, there is very little, as most results are mixed and aren't dominantly positive or negative, leaving this claim - unable to be true or false.
Teachers Unions and Student Performance: Help or Hindrance?. https://files.eric.ed.gov/fulltext/EJ795878.pdf. Accessed 17 Mar. 2023.