When we think back on our own school days, to the hours we spent on arithmetic, many of us remember laboring over pages of problems. Often these were pages of identical calculations, where only the numbers were varied. Or we worked with flash cards until we could shout out the answers immediately and with no mistakes. This kind of work was called "drill and practice." It was supposed to help us achieve perfect mastery of basic addition, subtraction, multiplication, and division. It was to ensure that we would forever remember how to perform the arithmetic operations we had been taught.