Is there some method to show attacks and defends and other statistics on board? I want to teach children basic rules of openings and show them some critical point in formation with some kind of visualization.

How can I show attack, defends, weak points or other statistics on board?
You could use Chessbase on a laptop to show games and positions. That would allow you to highlight critical squares and show possible moves with colourful arrows. Here is a description how to do this.