(2006) found that positive school climate was associated with students' academic achievement, after controlling for SES. Contrastingly, a negative school climate has been found to reduce student participation in school activities and student learning (Chen and Weikart, 2008).
Brackets. in quotes, square brackets show that the writer changed the original source. you might use them to change an ambiguous pronoun (such as "he" or "they") to a specific person or group (such as "abraham lincoln" or "school teachers"). they're also used to modify the phrasing of the original source to fit your sentence, such as changing a verb from from present tense to past tense.
