Click on the image at right to get the lesson app with instructor notes. Or you can install right from here by clicking the logo below:
In the first module, students will use models such as negative counters and number lines to understand multiplying by negative numbers, including some fractions and decimals. Students see the reason for ‘negative times negative equals positive’ as preserving the Distributive and Zero Properties.
In the second module, students will investigate slope using an interactive graphing tool. The tool shows that rates of change can be modeled as right triangle ‘steps’, with all the points on a line. The height and width and direction of the right triangles can be interpreted to obtain the slope of a line. Students model contexts using this interactive grapher.
Finally, in the third module, students will connect what they know about multiplying with negatives to divide with negatives. Students are encouraged to strengthen their multiplication fact knowledge if they have trouble with this section. Students show the quotients of a variety of different problems.
Module 1 Video
This video shows two models for multiplying a positive number and a negative number. Then it explains that –3 × –4 is equal to positive 12 in order to keep the Distributive Property and Zero Property intact. A demonstration of this is provided in the video.