Morse Toad is an android app based on the world renown Koch method that I really liked for learning Morse code. I can no longer find it in the Google Play Store. I have found it here. Looks like the guy is having issues keeping the app in the play store. Here is a Mirror of the (Morse Toad_v1.1)APK that I have run through VirusTotal.
I saw these video on youtube and thought I would post them here. I found them useful.