As demonstration, you can see here a simple 1x1 trainer program for kids. This uses also the 128x64 OLED display mounted below the Calliope mini board.
A random calculation will be shown on the upper 5x5 LED matrix and also on the small OLED display and measuring the time is started. If the answer is known, either button A or B should be pressed and the time measurement is stopped. The kid has 12 seconds time in total for answering the small arithmetic puzzles.
Now, the correct answer will be shown, and the kid must press button A, if he/she did the calculation correctly, otherwise button B. The reward for a correct answer is 1 point.
If the provided 12-second time-frame is over, the number of collected points will be shown.