I was given my first credit card when i was in 7th grade for "emergency use only." Of course I used it whenever possible, but I only had a $300 limit. At that age it is a lot of money and it would take me a looong time to be able to max it out. As i got older and started realizing that $300 is NOT a lot of money, It would max out quicker. My advice is if you are making the decision to give your child a credit/check card, go with a credit card. With my credit card I have never had any problems because when I max it out, I cannot charge anymore, and I believe that is what you should teach your kids, when you're out of money, theres nothing left to spend. As compared to a debit/check card, 99.99999% of banks have overage charges so if you spent $.01 over what you have in your account, they make a charge. (BoA charges 35)
Keeping in mind that I am only 17 years old, this is not a biased opinion because i too believe that I was much better at rationing and keeping track of my money when I only had cash. A "Emergency Only" Credit Card i believe IS a good decision once your child has proven that he/she is EXTREMELY responsible and knows that it IS only for emergencies. I have a belief that you should let your children (once they reach a more mature age) live their life and make their own decisions because THAT is how they will learn about the real world. I know more now because my mom let me make my own choices and made me deal with the consequences and I am more thankful for that.