The evolution of a pervasive negative view of immigrants and its role in classroom achievement in the United States is described in this paper; beginning in the crowded urban secondary classrooms of the 1800s, to IQ testing in the 1920s that identified many as morons, imbeciles, or idiots, and to an English-only view that permeates public and political views of teaching and learning. It is argued that categories such as ELL are ill-advised because they obscure diversity and inform neither instruction nor research because they are unidimensional and misrepresent important underlying diversity. It is argued that evidence-based strategies should inform teaching and learning, but that evaluating research is the purview of teachers themselves, including conducting classroom-based action research to test recommended strategies. Concludes with general guidelines to evaluate research.