Using Variables

Teacher Portal

Teacher Toolbox - Facilitating the Draw Square Sides 3 and 4 Page

#### What the Teacher Will Do:

• Instruct students that they will continue to work in their groups to follow the steps on this page.
• Circle the classroom as students work through the steps on this page and answer any questions that arise.
• Students will let you know when they are ready for their check in. Guidance for this check in is provided in a Teacher Toolbox at the bottom of this page.
• Once all groups have finished testing their projects and have drawn a square, bring the groups together for a whole-class discussion. Guidance for this discussion is provided in a Teacher Toolbox at the bottom of this page.

In VEXcode V5, follow the steps in this video to add another [Linear move] and (Add) block to the project. These blocks are used to code the arm to move 2 inches from the starting x and y-values, drawing the third side of the square.

Download and run the project. The arm will draw three sides of the square by moving 2 inches from the starting x and y-values.

If your arm did not draw these three sides of the square, notify your teacher.

Once you have finished coding the arm to draw three sides of the square, stop the project.

Follow the steps in this video to add another [Linear move] and (Add) block to the project. These blocks are used to code the arm to move back to the starting coordinate, drawing the fourth side of the square.

Download and run the project. The arm will draw all four sides of the square by moving the arm back to the starting coordinate.

If your arm did not draw all four sides of the square, notify your teacher.

Once you have finished coding the arm to draw all four sides of the square, stop the project and check in with your teacher.

Teacher Toolbox - Troubleshooting

If groups are finding that the marker does not draw as expected on the Workcell when they run their project, try the following troubleshooting techniques.

1. Change the z-value in the startZ variable.
1. Your dry-erase marker may not reach the surface at point 2. Have students set lower z-values, like 1.5 or 1, and test the project.
2. Check the mastering values.
1. Instruct students to check that the mastering values they recorded in their engineering notebook during Seek match what is in the [Set mastering] block.
2. If the problem still persists, have students follow the steps in Seek to rerecord their mastering values.
3. Check the VEXcode V5 project.
1. Have students compare their project to the video on this page and ensure the order of the blocks match. Make sure students are re-downloading their project each time they make a change and before they run the project
4. Check the build.
1. There may be a mechanical issue with your Workcell. Instruct students to look at the Lab build instructions first and verify that the additions to their Workcell from Lab 4 match.
2. Have students go back to the Lab 1 build instructions for a complete look at the build and check that all elements match. Even one small detail being wrong can affect the movement of the arm on the Workcell.

Teacher Toolbox - Check in

Review the following with the group during their check in:

• Ensure groups added the (Add) blocks in the correct places in the project. The fourth [Linear move] block should have an (Add) block for the y-variable, and the fifth [Linear move] block should not have any (Add) blocks, as this should just be the starting coordinate.

• Ensure the marker touches the whiteboard surface when students run the project. If the marker does not come down far enough, tell students to adjust the starting z-value in the [Set variable] block for the startZ variable.

If groups finish early, have them add onto their project by doing one or more of the following:

• Have groups add additional [Linear move] blocks and use (Add) blocks with the startZ variable to pick the marker up off of the whiteboard.
• Have groups add additional blocks to their project to draw two diagonal lines through the square.

Teacher Toolbox - Discussion

After groups have coded the arm of the Workcell to draw a square using variables in VEXcode V5, engage the class in a discussion about their experience coding and their observations.

• Begin by asking groups to share with the rest of the class what the square on their whiteboards look like. If time allows, ask groups to run their project to show the arm drawing a square for the rest of the class.
• Then ask groups to share any observations they had while using these variables. Ask students questions such as:
• How were variables used in this project? Students should note that these were used to store the starting coordinate for their square in the project.
• How was the (Add) operator block used in this project? Students should note that these were used with the variables to move the arm 2 inches in the x and y-direction to draw a square on the Workcell.
• Inform students that you will be using variables in future labs to store values so the arm on the Workcell can move to different positions in an accurate and repeatable manner.