Most of us get really excited for our students when they find the correct answer. Obviously for some questions, there might be more than one and maybe there is no wrong answer. We ask the question and celebrate when one of our students comes up with an appropriate answer and then we move onto the next question. Do you ever ask them HOW they knew the answer?
For me, this is just as important as the answer itself. By asking a student how they know something, they have to find words to explain their thinking. This is a whole other skill. It also helps them to be aware of how they think. We tell ourselves we 'just know' something because we haven't thought about how we know it. What signs did we see? Were there any words in the text that gave us a clue? Is there a pattern in those numbers? Ask students to explain their thinking.
Another benefit of asking 'How do you know?' and perhaps the most important, is that there is probably a student sitting in that classroom, who didn't know the answer, who didn't see those signs and who doesn't 'just know'. They will probably sit there quietly while you nod and smile and say to the other student 'That's right, well done' and never speak up to say 'I don't understand'. If we ask, 'How do you know?', then maybe that student will begin to see those signs, to see those patterns they had previously missed. You could ask another student 'How else do you know?'.
It also informs you of how your students think and future planning. What do your students look for? Do you have to re-word your questions? Have they mastered a thinking skill? Do you need to introduce another process of looking for answers? Have they completely missed the aim of your lesson?
You may even get your students into the habit of saying the right answer and giving you a reason without having to ask. 'I know because...'.
I am sure many of you do ask that question, generally on a one to one situation or perhaps for assessment. Think about asking as a group, the benefits can be amazing.