Construct It!
Students use simple household materials, such as PVC piping and compact mirrors, to construct models of laser-based security systems. The protected object (a "mummified troll" or another treasure of your choosing) is placed "on display" in the center of the modeled room and protected by a laser system that utilizes a laser beam reflected off mirrors to trigger a light trip sensor with alarm.
Student teams create laser-based security system models to protect the school's treasured troll.Copyright 2008 Terry Carter, Vanderbilt University
While the students are building their own alarm system it is important for them to consider how mechanical and civil engineers would go about building this system in reality. Lasers are used in manufacturing warehouses where industrial products are created by mechanical engineers. They can be used for accurate and efficient cutting and welding purposes. The PVC pipe the students use could be substituted with a metal that would have been cut with a laser! Students are prompted to think like engineers in the post-activity assessment questions 5 and 6, considering the real-world means of preparing materials and safety hazards when using lasers.
After this activity, students should be able to:
- Apply laser properties to construct a security system.
- Understand and describe how the system works.
- Understand how a beam of light can control other devices.
This activity also meets the following Tennessee Foundations of Technology educational technology content standards: 2.1, 3.2, 3.3, 3.4, 5.2, 5.3, 7.1, 7.2 and 7.3
This activity also meets the following International Society for Technology in Education (ISTE) standards: 1.1, 1.2, 2.2, 2.3, 3.1, 3.2, 6.1, 6.2; see http://www.iste.org/AM/Template.cfm?Section=NETS
- Students will develop an understanding of the attributes of design.
Grades K-12
Do you agree with this alignment? - Students will develop an understanding of engineering design.
Grades K-12
Do you agree with this alignment? - Modeling, testing, evaluating, and modifying are used to transform ideas into practical solutions.
Grades 6-8
Do you agree with this alignment? - Make two-dimensional and three-dimensional representations of the designed solution.
Grades 6-8
Do you agree with this alignment? - STEL-4N Analyze examples of technologies that have changed the way people think, interact, and communicate.
Grades 6-8
Do you agree with this alignment? - STEL-7Q Apply the technology and engineering design process.
Grades 6-8
Do you agree with this alignment?
- MS-ETS1-1 Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
Grades 6-8
This resource focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices- Define a design problem that can be solved through the development of an object, tool, process or system and includes multiple criteria and constraints, including scientific knowledge that may limit possible solutions.Do you agree with this alignment?
Disciplinary Core Ideas- The more precisely a design task's criteria and constraints can be defined, the more likely it is that the designed solution will be successful. Specification of constraints includes consideration of scientific principles and other relevant knowledge that is likely to limit possible solutions.Do you agree with this alignment?
Crosscutting Concepts- The uses of technologies and any limitations on their use are driven by individual or societal needs, desires, and values; by the findings of scientific research; and by differences in such factors as climate, natural resources, and economic conditions.Do you agree with this alignment?
- All human activity draws on natural resources and has both short and long-term consequences, positive as well as negative, for the health of people and the natural environment.Do you agree with this alignment?
Do you agree with this alignment? - Define a design problem that can be solved through the development of an object, tool, process or system and includes multiple criteria and constraints, including scientific knowledge that may limit possible solutions.
- MS-ETS1-2 Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
Grades 6-8
This resource focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices- Evaluate competing design solutions based on jointly developed and agreed-upon design criteria.Do you agree with this alignment?
Disciplinary Core Ideas- There are systematic processes for evaluating solutions with respect to how well they meet the criteria and constraints of a problem.Do you agree with this alignment?
Do you agree with this alignment? - Evaluate competing design solutions based on jointly developed and agreed-upon design criteria.
- MS-PS4-2 Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.
Grades 6-8
This resource focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices- Develop and use a model to describe phenomena.Do you agree with this alignment?
Disciplinary Core Ideas- A sound wave needs a medium through which it is transmitted.Do you agree with this alignment?
- When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object's material and the frequency (color) of the light.Do you agree with this alignment?
- The path that light travels can be traced as straight lines, except at surfaces between different transparent materials (e.g., air and water, air and glass) where the light path bends.Do you agree with this alignment?
- A wave model of light is useful for explaining brightness, color, and the frequency-dependent bending of light at a surface between media.Do you agree with this alignment?
- However, because light can travel through space, it cannot be a matter wave, like sound or water waves.Do you agree with this alignment?
Crosscutting Concepts- Structures can be designed to serve particular functions by taking into account properties of different materials, and how materials can be shaped and used.Do you agree with this alignment?
Do you agree with this alignment? - Develop and use a model to describe phenomena.
Materials each group requires.Copyright 2008 Terry Carter, Vanderbilt University (right) 2009 Denise W. Carlson, College of Engineering, University of Colorado Boulder
Each group needs:
- 20 feet (6 m) of half-inch PVC pipe cut into eight 18-inch (~45 cm) and four 24-inch (~60 cm) sections (PVC pipes available at hardware stores)
- 8 three-way PVC pipe corner connectors
- 6-8 PVC pipe "snap-T" connectors and/or 90-degree street elbows (for attaching mirrors)
- 6-8 compact mirrors (available at discount, drug or gift stores for ~$1.20 each, example source: CTA https://www.goodybeads.com/store/products/Z003407.htm)
- 1 laser trip sensor alarm kit
- sticky tack (reusable adhesive), 1 package (available in stationery/school supplies section at discount, office supply and drug stores)
For the entire class to share:
- (optional) rubber troll doll (available at toy stores) or make up your own treasure to protect
Note: A US$ 36 per group cost for non-expendable items includes PVC pipe, pipe connectors, 90-degree elbows, and compact mirrors. To reduce costs, groups may share supplies.
Basic understanding of light properties (especially reflection) and how lasers work, as provided in this unit's lessons 2 and 3, Learning Light's Properties and Laser Types and Uses, and their associated activities. An understanding of the engineering challenge and infomercial expectations outlined in lesson 4, Security System Design.
At the beginning of this unit, we received a challenge from our principal to create a security system to protect a valuable troll found on the school grounds. After being presented with this engineering challenge, we explored the necessary light and laser scientific properties so we have the information needed to devise a solution.
(This activity begins the Test Your Mettle phase of the legacy cycle.) Today, you will design and build a working security system using only the materials available, which shows whether you understand the properties of light and lasers and are able to apply these concepts to solving the challenge. Following the building stage of our challenge, you will test your designs and have an opportuniry to re-design and re-test. At the end, you will each answer questions to be turned in for a grade.
After this activity, we will Go Public. To do this, your team will create an infomercial to convince us that you have created the most reliable and cost-effective design.
Before the Activity
- Gather materials and bundle them in groups for student use.
- Assign costs for all materials (i.e., unit price) so students can determine final cost.
- Arrange for level working areas for students to construct their models.
With the Students
- Describe the assignment to students and explain the materials provided.
- Divide the class into groups of three or four students each.
- Have students sketch their designs down on paper before they build.
- Give enough time for students to construct a working model of a laser trip sensor system.
- Have students test their designs and re-design if necessary.
- Ensure students are keeping track the cost of their designs.
- Have students share their designs and compare other team's designs and discuss how well their solutions meet the challenge requirements.
Copyright 2008 Terry Carter. Used with permission.
(left) Example student-designed security system model with one mirror attached. (right) The laser with trip sensor.Copyright 2008 Terry Carter, Vanderbilt University
Making final adjustments to the mirrors and laser.Copyright 2008 Terry Carter, Vanderbilt University
- laser
- A device that emits coherent light through a specific mechanism.
- light sensor
- A device used to detect the presence of a light source.
- model
- A scaled representation of an actual system.
Post Activity Assessment
Summary Written Test: Have each student answer the following questions and submit them for grading. In addition to the design process, these questions address the Test Your Mettle phase of the legacy cycle.
- Why did you select the type of laser you used in your security system design?
- What other technologies might make use of the laser you have used in this design?
- If you were to change roles and act as the thief, how could you outsmart your design?
- What is the purpose of the trip sensor?
- If you were a mechanical engineer building this system on a life-size scale using a metal frame, what type of machinery would provide the most accurate cuts?
- As an engineer, it is important to consider the safety of the system you have created; could anyone be harmed once your system is implemented?
If students show an interest in security systems, contact a local security system consultant to demonstrate and discuss various systems.
Have students create advertising commercials that sells potential buyers on their systems.
- For lower grades, provide more time for construction.
- For upper grades, provide less time for construction, using it as a real-world limitation.
Dictionary.com. Lexico Publishing Group, LLC. Accessed August 7, 2008. (Source of vocabulary definitions, with some adaptation)
Contributors
Terry Carter; Meghan Murphy
Supporting Program
VU Bioengineering RET Program, School of Engineering, Vanderbilt University
Acknowledgements
The contents of this digital library curriculum were developed under National Science Foundation RET grant nos. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.
Copyright
2013 by Regents of the University of Colorado; original © 2008 Vanderbilt University