Very simply; Once a day, for no more than 15 minutes, complete a Number Talk.
What is a Number Talk?
Simply put, a Number Talk is a "naked number question" where students must use mental math to arrive at the answer. This tasks removes the myth of "there is only one way", or "there are better ways than others to do math" and instead ensures that all students are aware that each of them have some sort of mathematical insight to offer everyone else in the class.
Here is an example...
In Grade 2, Jennifer Smith put this up on the board and asked "How many dots are there?".
After most of the students said "7", she asked "How did you count them?", and this begins the Number Talk. I will let her share her story:
I was surprised that they had this many different ways of counting the dots and my class had no trouble explaining their thinking. I even had a girl; say 5. I was careful and said come and show us and she pointed to the middle 5 and then said oh ya and 2 is 7.
Now the cool part!!! 2 girls even asked to stay in during lunch and continue to count the number of ways to count to 7, (This is Grade 12 Math outcome!!)
Number Talks are a great way to get students talking, explaining, reasoning and ultimatley arriving at a deep conceptual understanding of how numbers work. If you are interested in knowing more I would suggest you read the following book: