Math Practice #2
Reason Abstractly and Quantitatively BY Hart Miller
I can think about numbers in many ways!
Contextualize and Decontextualize
Decontextualize-words into numbers
These are examples of
What It Is
More generally, Mathematical Practice #2 asks students to be able to translate a problem situation into a number sentence (with or without blanks) and, after they solve the arithmetic part (any way), to be able to recognize the connection between all the elements of the sentence and the original problem. It involves making sure that the units (objects!) in problems make sense. So, for example, in decontextualizing a problem that asks how many buses are needed for 99 children if each bus seats 44, a child might write 99÷44. But after calculating 2 or 11 or 2¼ or 2.25, the student must recontextualize: the context requires a whole number answer, and not, in this case, just the nearest whole number. Successful recontextualization also means that the student knows that the answer is 3 buses, not 3 children or just 3.