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Number Line
Lab 2 - Number Values

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Materials Needed

The following is a list of all the materials and teaching resources that are needed to complete the VEX 123 Lab. First listed are the materials needed for the entire Lab, including the 123 Robot. In certain Labs, links to teaching resources in a slideshow format have been included. Not all Labs will include a slideshow. These slides can help provide context and inspiration for your students. All slides are editable, and can be projected for students or used as a teacher resource.

Materials Purpose Recommendation

123 Robot

For students to code during the Lab.

1 per group

123 Field

For teachers or students to arrange into a number line.

3 tiles per group

Dry Erase Markers

For teachers or students to write numbers on the number line.

1 per group


For students to use as manipulatives.

1 classroom set

Lab 2 Image Slideshow

For teacher and student context during the Lab.

1 for teacher facilitation

White board eraser

To erase the marks on the Tiles at the end of the Lab. 1 per group

VEX 123 PDF Printables (optional) 

To use as manipulatives to support student project planning and saving. 1 per group

Environment Setup

  • Print or create a list of addition problems for each group. These will be passed out to each group during the Play section. Problems should only have numbers 1-9, due to the spacing on the number lines.
  • Ensure each group has enough crayons to physically represent each number on their number line. Crayons are for students to use as manipulatives when solving the addition problems.
  • Create a number line field for each group - Click together groups of 3 tiles per group in a long row, to serve as the space they can use for their robot to travel on. Use the dry erase markers to mark the numbers on the tiles to create a number line.
    VEX 123 number line tiles
    Number Line Setup
  • Note: One button press moves the 123 Robot one robot length or space equal to one block on the 123 Field. Keep this in mind if you choose to create a number line on another surface.
one press to one motion
One Button Press = One Space Moved
  • To help students take turns and stay focused on the Lab activities, give students direction for how to take turns and share responsibilities during the Lab. For recommended groups of two, students can take turns pressing the buttons and placing the 123 Robot, and counting and placing the manipulative to check their answers for each new equation. For groups larger than the recommended two students, provide students with more specific roles. Examples of responsibilities for students in this Lab include: 
    • Counting out the necessary manipulative and placing them 
    • Placing the 123 Robot on the number line 
    • Pressing the buttons on the 123 Robot 
    • Shaking to erase the project 


Begin the lab by engaging with the students.

  1. Hook

    Begin by asking students to show you, “How many is 4?” Students should show what the number 4 looks like on their fingers. Ask the students to solve an addition problem (1 + 3) on their fingers. You can model this process by holding up 1 finger on one hand and 3 fingers on another hand. Ask the students how many fingers you are holding up total? Guide students through another equation (2 + 3) using the same steps as before.

  2. Demonstrate

    Demonstrate placing the manipulatives (crayons) next to their coordinating number on the number line. Emphasize that the crayons are now replacing our fingers as the representation of numbers. Students will be instructed to place crayons at the appropriate places on their number lines.

  3. Leading Question

    How can our crayons, 123 Robot, and the number line help us to solve the same addition problem (1+3=4) we solved with our fingers?


Allow students to explore the concepts introduced.

Part 1

The teacher will lead students through a guided practice of the steps of solving one addition problem together using the 123 Robot on the number line. The teacher will use the number line to show how to solve the same problem from the Engage section. The emphasis will be on starting on a number, moving a number of spaces equal to the number being added, then stopping on the sum. The teacher will then model how to use manipulatives to solve the same problem. The sum of the equation and the total number of manipulatives should match.

Video file

Mid-Play Break

Students will guide the teacher through the process of representing and solving an addition equation with the 123 Robot, the number line, and manipulatives based on the guided practice in Play Part 1.

Part 2

Students work in small groups to use the 123 Robot, the number line, and manipulatives (crayons) as tools to solve an addition problem on their own. Each group will be asked to solve an addition problem using the steps practiced in Play Part 1. The groups will check their answer using manipulatives.

Alternate Coding Methods

While this Lab is written to use the buttons on the 123 Robot to touch to code, it can also be completed using the Coder or VEXcode 123. If adapting this Lab for the Coder, give each group a Coder and the Drive 1, Drive 2, and Drive 4 Coder cards to create a project that moves the 123 Robot on the number line to solve an equation. For more information about how to use the Coder, see the Using the VEX 123 Coder Knowledge Base article. If modifying the Lab to use VEXcode 123, give students a tablet or computer and build projects using the [Drive for] block in VEXcode 123.


Allow students to discuss and display their learning.

A VEX 123 character

Discussion Prompts