The radical gen is easy to remember if you think of “magnet 磁” (cf. magnet 磁石 = じしゃく), where stones 石 are hanging at strings 糸 (simplified to 幺) [and fixed with a bracket 艹] behave mysteriously.
Tip: Go to the radicals that are contained in this character and learn all the characters with this radical systematically!
The app has many other functions, such as character selection according to difficulty, practice programs, handwriting recognition and success statistics!
