On average, males score higher on standardized tests while females make higher grades in school.  This is true for the 2004 SAT test takers.  The combined mean score for males is 1049 and 1005 for females.  Males taking the test have a mean grade point average of 3.19, females 3.35.  A reasonable assumption is to ascribe this anomaly to the human attribute of motivation. 

I attempt to indirectly measure male-female differences in this attribute of academic motivation by assuming ability plus motivation is equal to achievement.

SAT data are available to directly measure academic ability, or IQ, from combined SAT score distributions and academic achievement from class rank statistics by using the construct of diversity space developed by La Griffe du Lion (see Intelligence, Gender and Race).  I find females have a mean IQ of 0.186 standard deviations (or 2.8 IQ points) lower than males but surpass males in academic achievement by 0.12 standard deviations.

The distribution of motivation is then easily determined  from the difference between the achievement and intelligence distributions.  I find females have a mean academic motivation of 0.41 standard deviations higher than males.  Also, the dispersion of the distribution for females is less than their male counterpart by a ratio of 0.976.

These results imply that academically, there are more than twice as many highly motivated females than males ( i.e. above the male two standard deviation level of motivation).  Also, high school grades are determined approximately 38% by intelligence and 62% by motivation.  Girls make better grades because they are more motivated than boys and grades are determined more by motivation than intelligence.