This is a simple application which generates calculation tasks for every level. Optionally one can choose a directory from which randomly an image is taken and uncovered with each correct answer (my kids like it).
So far there is only addition and subtraction. However, the code can be easily extended. The software is written in standard C++ and uses Qt. It should run on OSX, Linux and Windows.
The example image (joke) is from Yair Chuchem. Thank you!