Instruction Guide: EV3 - Move until Near
In this lesson students explore the use of the Ultrasonic Sensor.
In this Lesson we have 1 Primary Instruction Resource:
- The resource is a EV3 Trainer lesson on the Ultrasonic Sensor called Move Until Near.
The EV3 Trainer has a lesson describing the Ultrasonic Sensor
Behaviors >Sensors > 4. Move Until Near
The EV3 Trainer Teacher's Guide references this on pages 43-49.
Students should be able to answer all the review questions at the end of each step and end up with a solid command of each parameter in the Wait-until-Ultrasonic sensor block configuration panel and an understanding of how the ultrasonic sensors works.
The Optional Activities below the review questions in Step 3 include a "Did You Know" which shows the operation of the Ultrasonic Sensor and "Try It" sections which dig deeper into the Sound Block and Wait-for-Ultrasonic parameters.
The EV3 Trainer Teacher’s Guide has additional reproducibles for those who have purchased the product. The reproducibles for Move Until Near can be found on pages 99-100.
As students progress through, have them document their milestones in the Move Until Near Task Assignment Sheet.
There are 3 challenges:
- Mini Challenge : Threshold Value Behaviors >Sensors > 4. Move Until Near > 3
- Mini Challenge : Backward Until Far Behaviors >Sensors > 4. Move Until Near > 4
- Maze Challenge: Behaviors >Sensors > 4. Move Until Near > C
Maze Challenge
Key learning to check for during sign-off includes:
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Ensure students have a basic understanding of the physics behind the ultrasonic sensor's operation:
- Ensure students understand ultrasonic means sound waves above the human-audible range
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But, they are still sound waves and behave as such:
- They bounce of hard surfaces
- They can be partially absorbed by soft surfaces
- They bounce differently off of flat vs round vs angled surfaces
- They can interfere with each other
- Comparison to a bat's echo-location connects with some students
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Have the students explain their choice of hardware design (how/where the Ultrasonic sensor was attached/positioned)
- If your maze walls are relatively short (made of 2x4's, or shorter) the prescribed Ultrasonic Sensor attachment may be too high for optimal performance.
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Revisit the concept of a threshold.
- With the Color Sensor, a threshold is usually calculated from a measured "light" and "dark" value
- With the Ultrasonic Sensor, a threshold is usually set based on some design constraint or desired outcome
- Ensure students can distinguish between these two and explain the difference
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Have students explain their program
- Start with their flowchart/pseudocode to get an overall view of the program
- Use the EV3-G program to show how each block was implemented
- Ensure the understand the the parameters in the Wait-Until-Ultrasonic Sensor block
- Ask how the Wait and Move block parameters were determined
- Encourage the use of comments in their program - at a minimum, the block labels in the flowchart or pseudocode should appear as comments in EV3-G
