## Absolute Value Word Problems

Students will be able to identify and describe absolute value. Students will apply knowledge of absolute value to write word problems involving absolute value. Students will program a GoPiGo robot in Bloxter to "act out" the word problems.

**Setup**

- Create number lines on the floor in inches (at least 20 inches total -- 10 inches positive and 10 inches negative. This can also be done by students during the lesson depending on the amount of time available.
- Attach a straw, small slip of paper, or pipe cleaner to the front of each GoPiGo to serve as a marker on the number line. This can be attached to the front or slipped through one of the holes in the acrylic body of the GoPiGo (see image below).
- Connect to one of the GoPiGo robots (the first problem on the handout will be completed as a class)
- Download the sample code attached below (.blox file) and copy it onto a USB jump drive. Place the jump drive into the robot you will be using with the class. If time is limited, put the file on a USB jump drive in each robot. This will allow students to make changes to the program instead of having to build it on their own from the beginning.
- Copy student handouts

**Introduction**

- Display the image below of scene from
*Ferris Bueller's Day Off*. Explain that Ferris and his friend Cameron have borrowed Cameron's father's Ferrari without asking. Cameron is worried that his father will find out that the car has been driven because the odometer will show how many miles they traveled. Ferris tells him not to worry because they can take the miles off by driving backwards. - Ask the students, "What do you think about Ferris' plan? Will it work? Explain your thinking.."
- Tell the students that it will not work since driving backwards is still driving. If they drove 100 miles (forward) and then tried to take the miles off by driving 100 miles backward, they would put on a total of 200 miles on the car. This can be shown mathematically using absolute value |100| + |-100| = 100 + 100 = 200

**Procedure**

- Tell students that absolute value is a measure of the distance a number is from zero. It is always positive. If you look back in the Ferris Bueller example, the backwards movement is written as a positive, however when we calculated the total distance traveled, we made it a positive. Ex. |100| = 100 |-100| = 100
- Tell the students that they are going to be investigating absolute value by visualizing it on a number line and by watching the robot act out each problem. Distribute student handouts.
- Connect to a GoPiGo robot and project the screen onto the board. Click on 'Code in Bloxter'. Click on Open file to open the example program (AbsoluteValueExample).
- Place the GoPiGo on the number line with the front facing the positive numbers and the marker on the robot pointing at zero. Ask the students what they expect the robot to do. See the image below for a breakdown of the program and blocks.
- Run the program and see if it matches what students thought it would do. Graph the movement of the GoPiGo on a number line (on the student handout). Write and solve the math problem shown connected to the print block. Last, work as a class to develop a word problem that matches the equation and program. A sample answer is shown below.
- Students will then work in small groups to build the sample programs, write and solve a word problem for the program, and to graph the movement on a number line. Last, students will create their own program using absolute value.

**Conclusion**

- Facilitate a class discussion about the uses of absolute value. How could absolute value be useful in real life? How could it be useful for a future program for the GoPiGo?

Last modified: Wednesday, 4 November 2020, 11:46 AM