what happens when you forget to say check in chess
Check (chess) In friendly games, the checking player customarily says "check" when making a checking move. Announcing "check" is not required under the rules of chess and it is usually not done in formal games. Until the early 20th century a player was expected to announce "check", and some sources of rules even required it (Hooper & Whyld 1992:74).
Pawn (chess) Unlike the other pieces, pawns cannot move backwards. Normally a pawn moves by advancing a single square, but the first time a pawn moves, it has the option of advancing two squares. Pawns may not use the initial two-square advance to jump over an occupied square, or to capture. Any piece immediately in front of a pawn, friend or foe, blocks its advance. In the diagram, the pawn on c4 can move to c5, while the pawn on e2 can move to either e3 or e4.