Discovered checks is lesson 4 of 6 in Discovered attacks, a tactics course suited to players rated around 1100 (improving players). A discovered check is the strongest form: the king has to deal with the check, so the piece that moved is free to do anything, even take the queen. 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
Black to move: mate in 2.
White to move: unleash a discovered check. (7 positions)
Black to move: unleash a discovered check. (2 positions)
Worked examples
Black to move: mate in 2. 1...exf4+ 2.Kf2 Bd4#. Moving the pawn uncovered a check from the rook on e8, so the pawn had a free move. Mate in 2.
White to move: unleash a discovered check. 1.c5+ Qxb3 2.axb3. Moving the pawn uncovered a check from the bishop on b3, so the pawn had a free move. You come out 6 points ahead in material.
chessGM