The Two-Rook Ladder Checkmate
The ladder checkmate (also called the "lawnmower" or "staircase" checkmate) is the easiest checkmate pattern in chess. With two rooks, you don't even need your king, the rooks take turns driving the opponent's king to the edge.
The method
The rooks alternate, each one cutting off one more rank (or file). Rook 1 gives check on one rank. The king moves to the next rank. Rook 2 then gives check on that rank. The king is pushed back. Repeat until the king reaches the edge and checkmate is delivered.
Tips
Keep the rooks far from the enemy king to prevent captures. If the king approaches a rook, simply move that rook to the other side. The king cannot escape the ladder once it starts. This checkmate works even if your own king is on a1, it doesn't need to participate.