Left: water 氵, right: to chop 斩 (For the vehicle 车/車, use an axe 斤 to chop it)
Mnemonic
("Constant dripping wears the stone") Water can "chop", but only gradually. [Or due to rost: Water (damages) vehicles and axes: Gradually and little by little]
The app has many other functions, such as character selection according to difficulty, practice programs, handwriting recognition and success statistics!