According to Amazon,
Special pricing is available on select Kindle Fire tablets to Amazon Student members with an active Prime account (six months free or $39/year plan). Join Amazon Student or start your discounted Prime membership to take advantage of this discount. The promo codes below will become available 24 hours after activation of your account, through September 1. New members, don’t forget to check your .edu email and verify your account.
How to Take Advantage of This Offer:
1. Place one of the tablets below in your cart.
2. At checkout, enter the appropriate promo code when prompted:
If you are an Amazon Student member in a free or paid Prime plan, the discount will be applied to the corresponding item in your cart.
3. Complete your order before this promotion expires at 11:59 p.m. PST on September 1, 2013.