I knew there was a way, but just not exactly how until I read the below trick by Chad.
Unlike the first commenter who thinks the trick only works when you purchased the app when it still supported older iOS versions, the trick also works when you haven’t purchased an app before. I donated an old iPad 1 after wiping it clean. The above method allowed the new user to install for instance Google Drive and other apps (but not Google+: that one refused).
- On your iPad 1, go to: “Settings” ==> “Store” ==> under “Apps” make sure it says ‘OFF’.
- Go onto your computer (it doesn’t matter if you’re using PC or Mac) and open iTunes software.
- Then go to the iTunes store and download all the apps you want to be on your iPad.
- Ensure iTunes on the computer and your iPad are both signed into the same Apple ID, and the iPad is connected to internet.
- On your iPad go to App Store ==> Purchased ==> click on an individual app you want to install.
- Once you select install you’ll get a message pop up that says:”The current version requires iOS 6.1 or later, but you can download the last compatible version.”, choose “Download”
–jeroen
via: How to install apps which require iOS 6 on a 1st gen. iPad? – Ask Different