> That is entirely the point. The number line is awkward for multiplication.
Strong disagree. The number line is one of the best tools for understanding multiplication of numbers (not just whole numbers, but any decimal). The problem is that it is no longer taught. Example: American rulers have both metric (cm) and Imperial (inch) units. You can use it to visually multiply and divide by 2.54.
To generalize multiplying positive numbers x and y, (1) Mark x on a number line, (2) create another number line with the number 1 placed where x would be on the original line, (3) find y on the new number line, and (4) the corresponding point on the original line is the product x*y. The point: Multiplication is scaling (stretching, shrinking, whatever you want to call it). The Common Core tries to address this.
Strong disagree. The number line is one of the best tools for understanding multiplication of numbers (not just whole numbers, but any decimal). The problem is that it is no longer taught. Example: American rulers have both metric (cm) and Imperial (inch) units. You can use it to visually multiply and divide by 2.54.
To generalize multiplying positive numbers x and y, (1) Mark x on a number line, (2) create another number line with the number 1 placed where x would be on the original line, (3) find y on the new number line, and (4) the corresponding point on the original line is the product x*y. The point: Multiplication is scaling (stretching, shrinking, whatever you want to call it). The Common Core tries to address this.