When choosing apps I evaluate them using educational criteria.
Does the game reinforce concepts in the same way I have presented to the student?
I want consistent input.
Is the content educational, or just entertaining?
Games can be addictive. An educational purpose is key to any app.
Are there different levels?
I group students into very general levels: Elementary, Intermediate, Advanced. I categorize the apps in the same way.
What age group is the app geared to?
Cute graphics for a 1st grader might not be so appealing to a 6th grader.
What is the cost?
Beta versions are usually free but once they are put on the market, the cost may be a factor for families. This is something parents have to decide for themselves.
I have many, many apps that I have students use during their tech lab time. Here are some favorites.
EAR-TRAINING
Bubble Tones (all ages and levels)
Blob Chorus (all ages and levels)
All RCM ET/SR (Ear-Training and Sight-reading) books have online apps. The access code is printed on the back page of the book
RHYTHM
Rhythm Cat (all ages and levels)
Woodchuck Rhythm (early intermediate level, elementary school & middle school ages)
Rhythm Solitaire (intermediate level, middle school & high school ages)
NOTATION
Flashnote Derby (elementary level and elementary school ages)
Staff Wars (intermediate and advanced levels, middle school & high school ages)
THEORY
Dragon Scales (late elementary, intermediate levels, elementary and middle school ages)
Musicopoulos (intermediate and advanced levels, middle school and high school ages)
All RCM Celebrate Theory books have online apps. The access code is printed on the back page of the book
SIGHT-READING
Piano Maestro is excellent. I pay an annual subscription so students can use this at home.
PERFORMANCE
ASD the Amazing Slow Downer app records a performance. On playback you can slow the video down without affecting the pitch. (intermediate and advanced levels, middle school and high school ages)
Drum School Background rhythms that students can practice scales, arpeggii, chords to. (late elementary, intermediate, advanced levels, all ages)