In my math room there is one question, far and away, that I ask more often than any other. I'm not talking about a question or prompt such as "Could you show that to me in another way?" or "Why do you think that works?" those questions could be used in any classroom at any grade level in any subject.
I'm talking about a very specific MATH content question. I have been asking my first graders from the first day of school and I will continue up to the last.
It's quite simple. I draw a plus sign (or a minus sign) on the board and I ask "What is this? What do we say when we read it? WHAT DOES IT DO TO NUMBERS?" I ask this question day in and day out. I ask it when we are learning a new strategy. I ask it when we are practicing an old strategy. I ask this question to death. And there is an important reason why.
When teaching a new strategy for addition students need to know, above all else, that they are learning a strategy for efficiently putting parts together.
How many times have you had a student who answers a question such as 8 + __ = 10 with the number 18? You ask if the answer makes sense and the student says “Yes! I started with the big number and counted 8 more and got 18!” The students have learned a strategy or procedure and think that the plus sign indicates that they should perform that procedure when really the plus sign means they need to find an efficient way to put parts together- in the case of the above example they don't have both parts so they must do something to find out what they can put together with 8 to make 10.
By starting a new strategy with a quick conversation about the meaning of a plus sign and anchoring back to this idea throughout the development of the strategy students learn that they are developing a method for parts together- not a procedure for what to do when they see a + sign.