Subject: How does Sodiumpolycrylate or 'Water Loc' make water turn into a gel?

I am doing a science experiment for 3rd graders in my Elementary School 
teacher science course.  I want to use "Water Loc" (which is used in some 
diaper products, magic tricks, and by the fire department to soak up 
spills) to make water gel up.  I also want to turn the water back to a 
liquid by adding salt (I don't remember if I need to use iodized or 
noniodized salt).  My question is whether or not you could help me 
understand the chemical bonding and state changes a little better.  I did 
this in high school but I don't remember all the components that make it 
change into the gel and then back to the liquid with the salt.  Is there 
anyway that you could answer this to my understanding with any ideas you 
have for what I should present to the third graders as far as an 
explanation.  I have to give this experiment in about a week, so I would 
really appreciate if I could get an answer in that time.  Thank you for 
your help.

Re: How does Sodiumpolycrylate or 'Water Loc' make water turn into a gel?