It is often stated that girls are more quiet in the classroom.  This could be because males tend to be more aggressive and dominate conversations.  While many women are working to change these patterns and speak up, there are ways teachers can help girls gain confidence in the classroom from a young age.  Girls are just as capable and tend to do just as well in male-dominated classes, they are just quieter in the actual classroom atmosphere.  Teachers should make a point to call on equal students of both sexes if they feel this is a problem.  Wait-time is a big issue.  Teachers should not just always call on the first students who raise their hands because other, quieter students might be forming opinions during that time and just need a little longer to think.  Include everyone in course discussions, not just those who are the most outspoken.  This is true for boys and girls. It would become problematic the other way around if teachers started only calling on girls to make them feel comfortable.  Everyone's voice deserves to be heard.

http://bokcenter.harvard.edu/docs/TFTwomen.html

     This is an article from a study done at Harvard on women in the contemporary classroom.  It gives several valuable tips for giving girls and boys equal voices in class discussions, and ways to handle various situations where girls, or shy students in general are not speaking up that could be valuable for all grades.

     Another important consideration to remember is not to single girls out.  Don't make it obvious that you are intentionally trying to call on girls.  That will make the girls embarrassed.  It is never good to single students out, unless it is to give them positive feedback, and even then, be careful.