I deliberately make errors when I read to my class. When we read together and the kids are following along in their own books or on their own papers, I sometimes reverse the words. For example, if the paper reads 'up' I might say 'down'. The students are allowed and encouraged to shout out the correct word. It seems like such fun when I act so bewildered and they look forward to finding my mistakes. Those who weren't tuned in by the first error or two, certainly look forward to finding my mistakes and joining in with the others. This helps kids read at a faster pace than they might have done independently and makes a game of recognizing words out of context or silly add-ins.