Simplifying test questions so that they avoid unnecessarily complex English is the best way for states to include English-language learners in large-scale testing, according to the most prominent researcher on testing accommodations for such students. But other scholars say not enough studies have been conducted to know how states should alter standardized tests, or the conditions under which they are given, to most accurately assess children with limited English. Jamal Abedi, an education professor at the University of California, Davis, and the most-published researcher on testing accommodations for English-language learners, recommends that states devise separate versions of their academic tests using modified English. In that process, the wording of test items is changed so that students are not tripped up by complicated grammar, difficult vocabulary, or other linguistic obstacles. "That is the only accommodation that narrows the performance gap between English-language learners and non-English-language learners," Mr. Abedi maintains.