It is found that American students spend less than 15% of their time in school. While there's no doubt that school is important, a number of recent studies reminds us that parents are even more so. A study published earlier this month by researchers at North Carolina State University, for example, finds that parental involvement -- checking homework, attending school meetings and events, discussing school activities at home -- has a more powerful influence on students' academic performance than anything about the school the students attend. Another study, published in the Review of Economics and Statistics, reports that the effort put forth by parents (reading stories aloud, meeting with teachers) has a bigger impact on their children's educational achievement than the effort devoted by either teachers or the students themselves. And a third study concludes that schools would have to increase their spending by more than $1,000 per pupil in order to achieve the same results that are gained with parental involvement. So parents matter. But it is also revealed in researches that parents, of all backgrounds, don't need to buy expensive educational toys or digital devices for their kids in order to give them an advantage. They don't need to drive their offspring (,)to enrichment classes or test-preparation courses. What they need to do with their children is much simpler: talk. But not just any talk. Recent research has indicated exactly what kinds of talk at home encourage children's success at school. For example, a study conducted by researchers at the UCLA School of Public Health and published in the journal Pediatrics found that two-way adult-child conversations were six times as potent in promoting language development as the ones in which the adult did all the talking. Engaging in this reciprocal  back-and-forth gives children a chance to try out language for themselves, and also gives them the sense that their thoughts and opinions matter. The content of parents' conversations with kids matters, too. Children who hear talk about counting and numbers at home start school with much more extensive mathematical knowledge, report researchers from the University of Chicago. While the conversations parents have with their children change as kids grow older, the effect of these exchanges on academic achievement remains strong. Research finds that parents play an important role in what is called "academic socialization" -- setting expectations and making connections between current behavior and future goals. Engaging in these sorts of conversations has a greater impact on educational accomplishment. The word "potent" is closest in meaning to   _  .
powerful difficult necessary resistant