Compound Inequalities

Students will write programs to control the GoPiGo robot by using compound inequalities and light sensor readings.


      1. Copy student handouts.
      2. Ensure there is a way to have light and dark environments in the classroom.  This could be turning the lights on and off or covering the light sensor on the GoPiGo.


      1. Ask the students, what does the word compound mean?  Where have you seen it used? A compound  means 1) to put together (parts) so as to form a whole; 2) to form by combining parts.  Examples may include compound words (a combination of two or more words), a compound bow (a bow that uses a levering system of cables and pulleys to bend the limbs), a military compound (a type of fortification made up of walls or fences surrounding several buildings in the center of a large piece of land), a compound pulley (a combination of a fixed and moveable pulley), compound (chemistry - two or more different atoms bonded together), joint compound (a white powder of gypsum dust mixed with water to form a mud that is used with paper or fiber joint tape to seal joints between sheets of drywall, also known as joint cement)
      2. Tell the students that a compound inequality is a math sentence with two inequalities that are joined by either “or” or “and” (cliff notes). We will be using compound inequalities to tell the GoPiGo robot to react to different light sensor levels.


      1. Display the first example program using a compound inequality.  Ask the students, “During what light sensor values will the GoPiGo drive backward? ( L > 30 and L < 70) This could also be written as 30 < L < 70. During what light sensor values will the GoPiGo drive forward?” (L < 30 or L > 70) As a class, create graphs for both scenarios (drive backward, drive forward).
      2. Complete the same process for the next three examples. Discuss the difference between the “and” statements and the “or” statements.
      3. Students will then work in small groups to create programs in Bloxter using compound inequalities to tell the GoPiGo what to do in different light scenarios.  Students will follow the directions on the student handout to create their programs, write and graph the inequalities, and run their programs.
      1. Facilitate a class discussion about scenarios where compound inequalities can be used in real life to solve a problem.  Where could they be used using a light sensor?
      2. Collect student handouts to assess understanding of graphing and writing inequalities.

Last modified: Friday, 20 November 2020, 4:17 PM