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Little Red Robot
Lab 3 - Wolf Detecting Algorithm

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Launch the Engage Section

ACTS is what the teacher will do and ASKS is how the teacher will facilitate.

  1. Have students share their ideas about what they think the robot can detect. You may want to note ideas on the board to refer back to then during the discussion and demonstration. 
  2. Have students share their ideas. You may want to show them page 6 from the Meet Your Robot PDF Storybook (Google Doc / .pptx / .pdf) (on slide 5 of the Lab 3 Slideshow) to help them remember the difference between their eyes and the Eye Sensor, including that the sensor can detect certain colors. 
  3. As students share their ideas, guide them towards using colors as a distinction between Grandmother's house and the Wolf.
  4. Show the red Wolf, and guide students toward phrasing their reactions as If-then statements, as shown in the Asks. 
  5. Show students the "If red" Coder card (or use the 123 Poster for reference) and have students offer ideas and suggestions.
  1. In Lab 2, we changed our projects to make our robots 'scare away' the Wolf, or drive to Grandmother's house, depending on what we saw. Do you think our robot can detect the difference between the Wolf and Grandmother's house? Why or why not?
  2. We can see a lot of differences between the two with our eyes. What can our robot's Eye Sensor detect that could help it tell the difference? 
  3. Our robot's Eye Sensor can detect colors! It can detect red, blue, and green. How could we use that color detection to help our Little Red Robots tell the difference between the Wolf and Grandmother's house?
  4. What do we want our Little Red Robot to do when it detects the Wolf? (As students share ideas, recap if necessary - It sounds like we want the robot to detect an object and If it is red, then scare it away.) 
  5. We have a Coder card that says "If red". How do you think that could help us build a project to make the robot scare away the Wolf when it detects something red?


  1. InstructInstruct students that they are going to observe while you test the "If red" Coder card in their Coder project from Lab 2. Remind students that they will not be touching the 123 Robot or Coder yet, that this is just a time to watch what it does, so they can learn a little bit about this new Coder card. Turn on sound for this animation.
    Video file

    Note: You may want to foreground the project in Play Part 1 more fully, to ensure that students understand the project flow. You can use the Mid-Play Break prompts for discussing and stepping through the project on the Coder to help students understand the project flow with the "If red", "Else", and "End if" Coder cards. Have students predict the behavior of the robot before each Coder card is run, and facilitate a conversation about why they think that behavior will occur. Then connect the observed robot behaviors to the branch of the project that was run. (View this article to learn more about using the Step button on the Coder.) 

  2. DistributeDistribute just one 123 Robot with the Art Ring and decoration attached, and Coder, for demonstration purposes. Make sure that all students can see the Field, the 123 Robot, and the Coder. You will distribute 123 Robots, Coders, and Coder cards to student groups after the demonstration is complete.
    • First, wake the 123 Robot by pushing the wheels along a surface until you hear the startup sound, as shown in the animation below. Turn on sound for this animation. For more information about the 123 Robot, see the Using the VEX 123 Robot VEX Library article.
    Video file
    • Then, turn on the Coder and connected to the 123 Robot to a Coder. To connect the 123 Robot, press and hold the Start and Stop buttons on the Coder, and the Left and Right buttons on the 123 Robot for at least 5 seconds, until you hear the connected sound, and the indicator lights flash in time, as shown in the animation below. Turn on sound for the animation. For more information about the Coder, see the Using the VEX 123 Coder VEX Library article.
    Video file
    • Set the Little Red Robot on the Field opposite Grandmother’s house, in front of the red Wolf, as you did in Lab 2.
      Image of the Field setup with the Wolf between the robot and Grandmother's house
      Set up to test


    • Add the "If red" Coder card to the project from Lab 2, as shown in this image. Show students the project. 
      Image of the project from Lab 2 with an "If red" Coder card added
      Add the "If red" Coder card to the project from Lab 2 as shown


    • Start the project.
  3. FacilitateFacilitate a conversation about the behavior of the 123 Robot with the "If red" Coder card in the project. Ask questions about the sequence of the project, what the robot is detecting, and how that affects its behavior.
    • Whoa! Our robot just scared away the Wolf! How did it do that?
    • What did the Eye Sensor detect when the Little Red Robot got to the Wolf? Why did it honk? 
    • Why do you think the "If red" Coder card is after the "Drive until object" Coder card? What sequence of behaviors does this make our robot do?
      • Remind students that the robot needs to first drive to the object, next detect the color of the object, and then if it is red, play the honk sound. 
      • You may want to test the project with the "If red" Coder card in different places, and talk about how the sequence affects the behaviors of the robot.

    To help students grasp how the "If red" Coder card is affecting the project, you may want to run the project again with a different object, or talk through scenarios to explain why and how the if statement is working.

    • What do you think would happen if we ran this project and our robot was in front of a gray bunny? Would it scare away the bunny? Why or why not? 
    • What about if the robot stopped in front of Grandmother's house? Would it scare Grandmother? Why not? What if we wanted to do something different at Grandmother's house? Do you think we could? 
  4. OfferOffer positive reinforcement for good listening and conversation skills, as well as for students incorporating computer science vocabulary words like 'behavior', 'Eye Sensor', 'detect', or 'sequence' into their answers.
A VEX 123 character

Teacher Troubleshooting

Facilitation Strategies

  • Take Turns - Help students to take turns in their groups throughout the Lab. Suggestions to facilitate this include: 
    • To get started with the 123 Robot and Coder, one student can wake up with 123 Robot, while the other pairs the Coder.
    • During Play Part 1, have students alternate between starting the project and placing the 123 Robot and Wolf on the Field.
    • During Play Part 2, have students take turns inserting the Coder cards and starting the project.
  • Give Coder cards as they will be used - To help students stay focused on the learning about how the conditionals and loops in the project work throughout the Lab, you may want to only give students the Coder cards they need for each phase of the Lab. You can start with only the Coder cards in the project you build together in Play Part 1.
    • You can give students additional Coder cards during the Play section, as they are ready for additional challenges, so that they can explore changing the behaviors of the robot, or expanding on how they scare away the Wolf. 
  • Choose the reactions that are right for you - Consider your classroom's personality and environment in selecting options for students to use as their behaviors for scaring the Wolf and arriving at Grandmother's house. If too many sound effects will be disruptive, give students only the Action or Looks Coder cards as a way to lower the volume in the room. You can select which Coder cards your students can choose from, in order to best support your space and student needs.
  • Step to it! - The Step feature on the Coder is a great tool for slowing down project execution, and talking through the computer science concepts that make the project function as it does with your students. You can use the Step button at any time to run a project one Coder card at a time, and have students predict the behavior of the robot with each subsequent Coder card in the project. This is particularly useful to see the project flow with the "If red", "Else", and "End if" structure. View this article to learn more about the Step feature on the Coder.
  • Use printables as manipulative to support project planning - See the printable resources available in the VEX Library, and use them with students as they are planning and building their Coder projects. You could use the fill-in project and motion planning sheets for students to document their Coder cards and the path and/or reactions of the 123 Robot. You can also use the fill-in Coder sheet for students to write or draw their Coder cards to "save" their projects. 
  • Use Coder card posters to reinforce learning with the Coder - Highlight specific Coder cards, or refer to cards as you are teaching with the Coder card posters. Students can use these posters to review terminology as they are working with VEX 123. See the Using Coder Cards Posters in the Classroom VEX Library article to access these printable posters and to see more strategies for using them in your learning environment.