The Simple Answer
• There is the small window when students are smart and mature enough to truly absorb the content while still free from the 'challenges' of puberty (hormones).
The Academic Answer
• Piaget's stages of cognitive development, the 9 to 11 year-old child has entered the period of "concrete operations.” This time span is characterized by:
1. The developing capability of organizing thought processes and use of deductive reasoning to successfully anticipate consequences.
2. The ability to sort the abstract and more complex items by recognizing similarities is developing.
3. A longer attention span has set in (30-45 minutes), and the tween enjoys mental and physical challenges.
4. The ability to form an opinion based upon presented evidence and also mastering the ability to present their own beliefs to their peers and parents.(http://www.medicinenet.com/tween_child_development/article.htm)