Has somebody already made 'correct image/clock' app for kids? randomly placed?

Should it be also possible with a slider to navigate to the questions?

Yes, you can use the slider. But you need a discrete slider, so it jumped at the desired point.

Width = Fill container
Max value = 4
Step = 1

Text to color:

%D0%B8%D0%B7%D0%BE%D0%B1%D1%80%D0%B0%D0%B6%D0%B5%D0%BD%D0%B8%D0%B5