Compared to adults, children seem to be moving constantly．So it's no surprise that most parents who are quizzed about their child's physical activity level describe their children as fairly active．But a new study of nearly 2,000 British school children suggests that many parents overestimate the amount of physical activity their children are really getting．
The researchers equipped 1,892 British school children, ages 9 and 10, with accelerometers that measure all physical activity during a given time period．The research, known as the Speedy study collected the exercise data from children at 92 schools in Norfolk, England, between April and July 2007．
A child was regarded inactive if he or she recorded less than an hour a day of physical activity．Although the majority of children studied were getting enough physical activity, a sizable minority of children were not．Overall, 39 percent of girls and 18 percent of boys studied were getting less than an hour of physical activity each day．
But if you asked the parents of the inactive children to describe their child's activity level, the vast majority—80 percent—described their children as fairly or very physically active, according to the findings published in the American Journal of Preventive Medicine．Interestingly, the children themselves had more awareness about their lack of physical activity．Overall, 40 percent of children overestimated their physical activity．
But it wasn't the parents of overweight children who were most likely to guess wrong about physical activity levels．The parents who were most out of touch about their child's physical fitness were more likely to have children who were slim．Parents of girls were also more likely to overestimate physical activity．The researchers noted that parents should be educated about the importance of physical activity for children even if the child is not overweight．
"Parents of slim children appear to assume that their children are adequately active," the study authors reported．"Increasing awareness regarding health benefits of physical activity beyond weight control might help have a correct idea of physical activity levels and encourage behavior change．"
69．According to the Speedy study, what kind of children can be judged physically inactive?
A．Slim children．
B．Children with less than an hour a day of physical activity．
C．Overweight children．
D．Children out of touch with their parents for a long time．
70．What does the writer probably mean by saying "a sizable minority of children were not" in Paragraph 3?
A．The amount of children's physical activity is far from the writer's satisfaction．
B．Only a small number of children were not getting enough physical activity．
C．A small number of children didn't overestimate their physical activity．
D．The minority of children were not studied at all．
71．The passage is intended to ____．
A．encourage parents to fairly judge their child's physical activity levels
B．persuade parents to keep an eye on their children's weight
C．urge children to wear accelerometers during exercise
D．advise parents to keep in touch with their children