Automatic page selection (our target audience may not be able to operate buttons and switches) is accomplished by reading the resistance of photoresistors.
At this stage, the output goes to light emitting diodes. In the final version, songs will be played.
Holes are drilled in the board book and corresponding photo resistors are lined up in the back of the book.
When light strikes a photo resistor, the Arduino "knows" that page is active.
The "deepest page in" is the one that should be activated.
The electronics have to be minimized in size and tied to the music playback system. The "Turn it on when picked up" system also has to be installed.