All of the web pages are from the United States (and one about China), whose educational environment is different from ours in Taiwan.
Not all the writings take a fair stance.  Some wrote for the schools they represent.

• An academic report: K-12 Single-Sex Education: What Does the Research Say?

 
• Pro Single-Sex
1. Girl power Shanghai-style
2. What a Single-Sex School Is Really Like
3. Why Single Gender Education?  Because it is the BEST for Young Women!
4. School: No Boys Allowed (some cases from a site for girls only)

 
• Pro Co-Ed
1.  best of both worlds: a co-ordinate model

 
• A statistics which might be misleading.