The ability to deal with numbers and mathematical concepts reveals an interesting pattern of differences between girls and boys. Girls usually begin counting before boys. Throughout the primary-school years and middle school, girls are better at computational problems, whereas boys do better with math- reasoning problems. During this period, girls also tend to get higher grades. By high school, however, boys begin to perform better, especially at the higher levels of ability. Some psychologists believe this advantage is genetic, but others think that it may derive, in part, from males’ use of more effective strategies and their lower level of anxiety when approaching mathematics problems. It has also been suggested that the sex differences come about to some degree because girls view math as a male activity (and, therefore, have less interest in it) and because some parents and teachers offer greater encouragement to males in this area. Some studies support this analysis, but others do not. In this area, too, biological and socialization factors probably combine to produce the observed differences.