The two-rook ladder is lesson 1 of 3 in Basic checkmates, a checkmate course suited to players rated around 550 (complete beginners). Two rooks can mate without any help from the king. It has 2 interactive exercises: 1 find-the-move puzzle, 1 exercise playing out a mate. You play every move on a board and get feedback straight away. The lesson is free.
What this lesson explains
The ladder: one rook cuts off a rank, the other gives check on the next rank. They take turns, and step by step the king is pushed to the edge. Here the rook on b7 guards the 7th rank and the rook on a8 gives mate.
What you practise
Finish the ladder: checkmate in one.
Your turn to climb the ladder. Checkmate the king with your two rooks. The king will try to attack your rooks, so keep them far away from it!