单选题 In recent decades child specialists have tried more and more to help parents with their children''s school behavior. Schools of education 【B1】 tended to emphasize subject matter 【B2】 what the children are being taught, but attention increasingly is being paid to the children themselves. One area 【B3】 emphasized is the matter of a 【B4】 developmental or "maturity" level--that is, the child''s 【B5】 of readiness for starting school. Research demonstrated that a major 【B6】 of children who fail in school 【B7】 primarily because of their immaturity and their unreadiness for the work of the 【B8】 that law designates: age five for kindergarten, age six for first grade. Common sense 【B9】 us that not all five-year-olds have reached 【B10】 average level of performance expected 【B11】 age five. Thus many five-year-olds fail in kindergarten and six-year-olds fail in first grade 【B12】 because of a "learning disability" or "attention deficit disorder" but simply because 【B13】 are in a too-advanced grade. Experience has shown that the number of 【B14】 learners can be substantially reduced by a policy of 【B15】 every child''s readiness--that is, 【B16】 level before beginning school. This concept has 【B17】 widely. Many school systems now routinely provide not only readiness testing but also extra grade 【B18】 : pre-kindergarten or "developmental" kindergarten for a year 【B19】 full kindergarten; and pre-first grade for six-year-olds not fully 【B50】 for first grade.