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Teacher Toolbox icon Teacher Toolbox - Facilitating the Pass the Green Disk Page

What the Teacher Will Do:

  • Bring students together for whole-class instruction.
    • Explain to students how the green disk will move when they complete the project on this page. 
      • Walk students though each of the steps needed to move the green disk from the entry conveyor to being sorted in the green drop off location.
      • Watch the video on this page on how the green disk should travel through the conveyors and be sorted in the green drop off location. 
      • If students are struggling at any point as they are working on their projects, encourage them to re-watch the video of how the disk should travel.
    • Ensure all students are on the same page with the expectations of how the green disk will travel before moving on. Then, instruct students that they will be working together in their groups to follow the steps on this page.
  • Break students off into their groups to follow the steps on this page.
  • Circle the classroom as students work through these steps and answer any questions that arise.
  • As groups check in, ensure they have built their project correctly before moving on. Guidance for this check in is provided in a Teacher Toolbox at the bottom of this page.

The green disk, acting as an acceptable package or product, will move through the following path:

The green disk will begin at the entry conveyor in front of the Optical Sensor.

Green enter

Once the green disk is loaded onto the transport conveyor from the entry conveyor, it will pass in front of the load sensor. When the green disk passes in front of the load sensor, the diverter needs to be set to the 0 degree position in order to pass the green disk through the diverter.

Green diverter

Once the green disk passes through the diverter on the transport conveyor, it will pass in front of the pickup sensor. When the green disk passes in front of the pickup sensor, the transport conveyor will stop.

Pickup sensor

Once the green disk has stopped in front of the pickup sensor and the transport conveyor has stopped moving, the arm will pick up the green disk from the conveyor.

Green pickup

The arm will then move the disk to the green drop off location and sort the disk.

Green drop

The green disk will have followed this complete path to be passed through the diverter and sorted into the green drop off location.

Video file

Now that you have diverted the red disk off of the exit conveyor using sensors, you will now code the green disk to pass through the diverter on the transport conveyor, stop in front of the pickup sensor and then be sorted into the green drop off location.

Duplicate the stack of blocks attached to the {Define My Block} block for the red disk, and attach them to the {Define My Block} block for the green disk to create the stack of blocks shown in this image.

The parameters of these blocks will be adjusted to code the green disk to pass through the diverter on the transport conveyor and stop in front of the pickup sensor.

Duplicate blocks

Follow the steps in this video to edit the comments and parameter of the [Spin to position] block for the green disk.

These blocks will code the transport conveyor to spin forward until the load sensor detects a light value greater than the lower threshold value.

Then, once the green disk is in front of the load sensor, the diverter will be set to the 0 degree position to pass the green disk through the diverter on the transport conveyor.

Follow the steps in this video to edit the stack of blocks to pass the green disk through the diverter on the transport conveyor and stop in front of the pickup sensor.

These blocks will code the transport conveyor to spin forward until the pickup sensor detects a light value greater than the lower threshold value.

Then, once the green disk is in front of the pickup sensor, the transport conveyor will stop spinning.

Load a green disk onto the entry conveyor and download and run the project.

The disk will follow the shown path and stop in front of the pickup sensor.

Once the green disk is in front of the pickup sensor and the transport conveyor stops spinning, stop the project and check in with your teacher.

If the green disk did not follow the path shown, notify your teacher during the check in.

Green path

Teacher Toolbox icon Teacher Toolbox - Troubleshooting

If groups are finding issues with their conveyors and diverter moving when the green disk is detected, try the following troubleshooting techniques.

  1. Check the VEXcode V5 project.
    1. Have students compare their project to the images 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.define green disk my block code
      1. Ensure students are paying close attention to the parameters of the (Reflectivity of) blocks. These should match the low values they recorded for the load and pickup sensor on the previous page. If students are still having issues with their Line Trackers, have them adjust this threshold value and test again.
        threshold values
      2. Remind students to set the second (Reflectivity of) block to 'Pickup,' so the conveyors are set to stop once the green disk reaches the pickup sensor.
        pickup reflectivity block
      3. Ensure the [Spin to position] block for the diverter is set to 0 degrees. Students may accidentally leave it at 90 degrees or 9 degrees, which would not spin the diverter enough to allow the disk to pass through the diverter along the transport conveyor.
        set to zero
  2. Check the build.
    1. There may be a mechanical issue with your Workcell. Instruct students to look at the Lab 10 build instructions first and verify that the additions to their Workcell match.

Extend Your Learning icon Extend Your Learning

If groups finish early, ask them to try the following:

  • Sort one red disk and one green disk without stopping the project in between disks.
  • Sort one red disk and one green disk faster than the previous trial.
  • See how many red and green disks you can sort in one minute in random order without stopping the project.

Teacher Toolbox icon Teacher Toolbox - Check in

Review the following with the group during their check in:

  • Check that all groups have successfully gone through all the steps on the page. Ask them to run their project for you, so you can see the green disk pass through the transport conveyor and stop in front of the pickup sensor. If the project does not run as expected, see the Teacher Toolbox - Troubleshooting note above.
  • Ask students the following questions as students are presenting their projects.
    • How was the code different between sorting the red disk to sorting the green disk?
    • Did your project run the first time you tested it? If not, what did you change?
    • What is the purpose of the Optical Sensor in this project?