Plus-Minus Trainer is a learning software enabling children practicing
additions and subtractions on a device running Android.

Multiple training modes are provided for this cause:

+ Online mode: Exercise written addition and subtraction. Tasks and
Solutions are retrieved and respectively saved from a web server,
located at https://schule.learninglab.tugraz.at/plusminus/.

Following modes do not need internet access. The difficulty of the
randomly generated tasks can be changed in the application's settings.

+ Plus-Minus mode: Solving of randomly generated written additions or
subtractions.
+ Speed mode: Solving of randomly generated calculations within a
timebox of 60 seconds including a high score list.
+ Tree mode: Solving of three randomly generated Calculations connected
by a calculation tree.
+ Analogy mode: Solving of similar tasks (e.g. 5+2 and 2+5)
+ Symbolic addition: Solving of simple inline additions with auxiliary
symbols.
+ Symbolic subtraction: Solving of simple inline subtractions with
auxiliary symbols.