Probably one of the most heatedly discussed boards in my classroom: True or False?
Tackling misconceptions and insufficient explanations, pupils vote on whether they think the statement is true or false. At the end of the week the correct answer is revealed with an explanation.
My favourite moment had to be a gaggle of 1st years running to change their vote on the statement above, following a test on order of operations, as they realised they'd forgotten to divide before subtracting!
The statement bank can be found here - any more ideas greatly appreciated!