Why won't the new sketch feature in iOS 9 Notes work on my iPod Touch?

[iMore Question]

I have a 64GB 5th generation iPod Touch and upgraded its OS to iOS 9. I upgraded the Notes app and enabled Notes on my iCloud account. I can access the other new features (checklists, new formatting, and picture-taking) but not the sketch feature. Anyone know what the cutoff is for devices Apple considers too old for this feature? It seems silly that it wouldn't work on this device. It isn't THAT old!

 

[kch50428]

Sketch isn't available on the 3rd gen. IPad either...