Instructor makes the cards ahead of time; use the cards to call out. Could use words or picture cards. When a word is called, students click on the button. The board will inform the student when they have achieved four in a row for BINGO. Feel free to remix and edit the words or switch to pictures.
I came up with this idea because my students are motivated by games and activities on the iPad and they also do not know when they get BINGO. The board automatically randomizes the squares during the loading process at the beginning.