I am using Zagg Bluetooth Keyboard Case, which basically turns my iPad Air 2 to a mini laptop: https://www.zagg.com/us/en_us/keyboards/slim-book-keyboard-case
When I use applications for typing, by default the onboard keyboard is hidden. I can tap the "show keyboard" key on my bluetooth keyboard, type onscreen, then tap the "hide keyboard" button I mentioned in my previous post.
To see a demo of this, see animation below:
via GIPHY
Maybe you haven't updated to iOS 10.3.1, otherwise, could be the Bluetooth keyboard you're trying to use isn't compatible with iPAd.