Short exercises for arithmetic, language and telling the time. Works straight on the whiteboard, no account needed.
Countdown timer with large digits and a sound at the end.
Write and draw on the board, with markers, an eraser and lines or squares.
Split the class into random groups, by number of groups or by group size.
Guess the word letter by letter, with English word lists.
Connect four on the classroom board, with two players or against the computer.