I use these a lot. They’re not threatening, they’re fun, and they’re hugely informative. The set I use most often is a simple set of a couple of dozen cards, each with a
multiplication statement, e.g. 6×6=36. Some of the statements are true, but some, such as 8×8=63, are false.
I ask children to sort them into three categories, true, false, and don’t know or not sure. What’s particularly revealing is when children tell you why they put cards into the false pile. One child will say 8×3=25 can’t be true because the correct answer must be even; another will say it’s because neither number is 5.
It’s such a valuable activity that I’ve got plenty of other sets as well, with different numbers and operations.