Abstract: Connection systems for toy construction pieces, toy construction pieces, and toy construction kits. A connection system includes a male connection element and a female connection element. The male connection element includes a peg unit with a connector peg. The female connection element includes at least a portion of a connector core that defines a receiver cavity configured to receive at least a portion of the connector peg and at least a portion of a core shell. A toy construction kit for assembling a constructed assembly includes a plurality of toy construction pieces that collectively embody the connection system. A first construction piece includes the male connection element and a second construction piece includes the female connection element. The connection system is configured to selectively and repeatedly couple the first construction piece and the second construction piece to one another.