Double check is lesson 1 of 6 in Discovered attacks, a tactics course suited to players rated around 1100 (improving players). When the moving piece and the piece behind it both give check, no block or capture helps: the king has to move, and often it has nowhere to go. It has 10 interactive exercises: 10 calculated lines from real positions. You play every move on a board and get feedback straight away. The lesson is free.
What you practise
White to move: mate in 2. (6 positions)
Black to move: mate in 2. (4 positions)
Worked examples
White to move: mate in 2. 1.Qf5+ Kd8 2.Nc6#. Double check: the knight and the bishop on h4 both gave check, so only a king move was possible. Mate in 2.
White to move: mate in 2. 1.Nc7+ Kb6 2.Qc5#. Double check: the knight and the queen on e5 both gave check, so only a king move was possible. Mate in 2.
chessGM