Guzinta Math 7th grade Common Core lesson apps are compact math lesson plans designed to supplement your school or home mathematics instruction. Each math lesson plan contains detailed instructor notes to provide guidance and facilitate discussion about concepts between you and your student or students. Lesson plans feature video instruction, worked examples, guided practice, and some lesson plans feature interactive instructional simulations to help achieve peak cognitive engagement! Bookmark Guzinta Math and come back to see what's new. We'll be adding conceptual practice and science connections to each lesson plan, extending the suite of lesson apps, and much more.

Add and Subtract Negative Numbers

Click on the image at right to get the lesson app with instructor notes.

In this lesson, students will practice adding and subtracting negative numbers and solving word problems involving the addition and subtraction of integers. The positive and negative numbers are reflections of each other across 0 on the number line. Students will see that adding a negative is the same as subtracting a positive and subtracting a negative is the same as adding a positive.

Module 1 Video

This video shows a method called the Slingshot Method. This method encourages students to read an addition sentence as they normally would—as moving to the right on the number line. When the addition involves a negative, the right movement turns into a “pulling back” like on a slingshot, which, when released, moves in the opposite direction the number of units described by the (absolute value of the) second number.

Module 2 Interactive

To use the interactive tool, use your mouse to click on the rectangle marker and then, while holding down the mouse, drag to the left (subtraction) or right (addition). This draws out a kind of pull string which will generate a sum or difference once you release the mouse. The addition or subtraction expression above the number line changes as you move the mouse, to show you what sum or difference you will create. Releasing the mouse will move the rectangle marker to the sum or difference specified above the number line. This expression remains until you click and drag the mouse again.