A friend sent me this link to Savvy Source. (It is like Groupon.) For a little more than 2 more days you can purchase a Family Membership to the Discovery Center for $37.50. It looks like you have 6 months to redeem it, so even if you are paid up until February, you could buy it half price now and redeem it then. You can't use other discounts (like the teacher's discount) so make sure you know which on is better before you buy it as it says it is non-transferable. So so get in on the deal click here or copy and past this address:
Once you purchase it you can print off the paper that you need to take in with you right then or you can do it later by logging back into your account. So if you are not near a printer don't worry. You can print it out later.
PS - If it doesn't take you straight to the Nashville page, just pick Nashville from the drop down menu that you will likely see somewhere on the page.