Teams have a set of question cards stacked facedown in the center of the table.
The teacher selects one student on the team to be Showdown Captain for the first round. The Showdown Captain draws the top card, reads the question, and provides think time.
Working alone, all students, including the Showdown Captain, write their answers. Teammates signal when finished. The Showdown Captain calls “Showdown!”
Teammates show and discuss their answers. The Captain leads the checking. If correct, the team celebrates; if not, teammates tutor, then celebrate.
The person on the left of the Showdown Captain becomes the Captain for the next round.
Modification
Rather than cards, students can play Showdown with oral questions from the teacher, or with questions on a handout or questions displayed by a projector.
Source
Kagan, S. and Kagan, M. (2017). Kagan Cooperative Learning. San Clemente: Kagan Publishing, p.6.68.