Subject: How would space travel affect a child of any given age?

I am designing a problem-based learning unit for 6-12 students 
and teachers.  I am interested in the biology and physics 
associated with sending children into space.  Please consider the 
effects this might have on the unborn, infants, toddlers, 
preschoolers, K-2, 3-5, 6-8, and 9-12 graders.  I am particularly 
curious as to whether it is better for a pre or post-pubescent 
child to be chosen for a trip into space.  Please advise as to 
the length of time advisable for each age to spend in space.  
Thank you for your help in this matter.

Re: How would space travel affect a child of any given age?