When playing a game that requires verbal answers have players take turns giving answers. Players who know an answer may pass the answer by whispering.
Children are not always patient and sometimes it can be difficult while playing a game to prevent more able or more confident children from blurting out an answer. Participation is to be encouraged but not if it deprives another child of practise.
One possibility is to penalise players who "take over" another player's turn by disallowing the item in question. For example, when playing snake or centipede if one child answer's when it is another child's turn the flashcard is lost and becomes a tooth.
An alternative to penalising the enthusiastic player is to establish the rule that answers may only be passed by whispering. A player who knows an answer may whisper it to an adjacent player who in turn passes the whisper on until it meets the player whose turn it is . This has the advantage of involving more players while giving the player whose turn it is more time to think. It also serves to encourage less confident players to have a go rather than wait for someone else to jump in. Whispering answers allows a shy player to get help but still gently prods the player to actually speak.