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Number Line
Lab 1 - Adding with the 123 Robot

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Launch the Engage Section

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

  1. Write the equation 1 + 4 = ? at the front of the room.
  2. Have 5 students come stand at the front of the room to represent a number line. Each student should hold a number (with a sticky note or piece of paper).
    Five students holding up paper with 1 through 5 written on each paper.
    Student Number Line
  3. Model the equation 1 + 4 = 5 with the student number line. Start at the student representing 1, then count 4 over from the first student.
  4. Draw a number line on the board.
  5. Show the students the 123 Robot with the number line.
  1. What does 1 + 4 equal? (5) How do we know this?
  2. Have you ever used a tool before? A number line is a tool we can use to solve math problems.
  3. Count aloud with me as we count each classmate.  We start at the student representing the first number of the equation, which is 1, then we count forward the number equal to the second number or addend of the equation, 4.  We will stop on the sum, 5. 
  4. This is a drawing of a number line, which is what we made with our classmates to solve the addition problem.
  5. Can we solve an addition equation using our 123 robot with a number line? Let's find out! 


  1. InstructInstruct students that they are going to use the 123 Robot and a number line to solve addition equations. Let students know that first they will watch either a demonstration or an animation. Afterward, they will follow along with the teacher to practice using the 123 Robot and the number line together to solve an equation.

    Once they have practiced with the teacher, they will work with their group to solve an equation on their own!

    Video file
    • Then, demonstrate the steps or show the animation to illustrate how the 123 Robot will move on the number line to solve the equation 2+4=6. Highlight the following:
      • You will press the Move button 4 times for the number being added in the equation.
      • The 123 Robot is placed on the first number (2). 
      • Then, it will move the number of spaces equal to the second number (4).
      • If done correctly, it will land on the sum (6).
    Video file


  2. DistributeDistribute 123 Robots to each group.
    • If using shared number lines made with 123 Fields, assign each group to a number line. You may choose to set up all group number lines before the Lab to save time.

    example of a number line created with 123 Tiles
    Number Line on a123 Field

    • If you would like students to practice writing their numbers, model how to write the numbers 1-9 in the middle squares of the 123 Field with Dry Erase markers. Then, have students create their number lines.
  3. FacilitateFacilitate an inquiry-based discussion about how the robot moves along the number line. Ask open-ended questions directed at what the students observed in the demonstration.
    • How do you think the robot knows how far to move? What do you see that makes you say that?
    • Which direction does it move? Why do you think this is important?
  4. OfferOffer positive reinforcement for students showing good listening skills, and taking turns sharing their ideas.
A VEX 123 character

Teacher Troubleshooting

Facilitation Strategies

  • During the environment setup, you can set up each group’s number line with 123 Fields and the dry erase markers, or have the students write in the numbers to give them more practice creating a number line and writing numbers.
  • Tailor the addition equations given to the students in the classroom. Depending on their previous experience with math equations and number lines, students will have differing abilities and familiarity with addition.
  • If some groups seem to catch on quicker, have them begin combining addition equations to make multi-step equations in the Play sections.
  • 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 touch projects. You could cut out the touch button symbols and have students lay them out on their desk as they build their projects, or use the color-in sheet for students to color in the sequence of button presses in their projects.