13 Drawing a pawn ending
Black draws this ending by defending his control of the promotion square. To do so he uses the opposition to block the advance of the white king.
If the white king is behind or beside its pawn Black can maintain the opposition and by doing so hold the draw.
Now we go two moves back in a possible defence. The following position is the nucleus of the defence.. Black moves in such a way as to be able to take the opposition at the right moment.
After some time it is a forced draw because the position will have been repeated three times since the king has to protect its pawn. That is your goal.
Now practise defending in cases when the pawn is further back. The defensive method is the usual. If the white king advances, take the opposition. White then has to give a pawn check to gain space. But you know from the first example that this check helps him advance only as far as the sixth rank. From the seventh rank a check would stalemate BLack.