What goes up, must come down.
That is the question Old Dominion University doctoral student Mary Phelps first poses to disbelieving budding technologists and engineers aged 8 to 18 during engineering outreach summer camps or after-school programs. Then, primed by her story of the Three Little Pigs (Thompson, 2013) and a brief conceptual grounding in the basic physics of stationary mechanical structures, students brainstorm, design, build, and test a prototype structure. If time allows, they may then redesign, build, and retest an optimized one. This structural engineering design project can be adapted to fit 45-minute or greater time slots and groups of 10 to 100 students.
Wooden blocks are one of the first things most children begin playing with as they develop; they quickly learn that in order to build a taller tower, they must carefully place one block above the other so that their tower balances long enough for them (or an overly eager sibling) to knock it down. Blocks often make way for LEGOs, Lincoln Logs, or other preformed building components. Once past five years old, however, children have little exposure to building activities, although they will spend most of the rest of their lives living, working, and learning in one or another type of structure built for a specific purpose. Phelps' lesson gives them that exposure to building structures in a very simple manner.
Standards for Technological Literacy (STL), (ITEA/ ITEEA, 2000/2002/2007) suggests that by the time students graduate from high school, they should understand the importance of design constraints in evaluating and purchasing structures such as homes and offices; engineers understand this process of balancing requirements, needs, and desires as making trade-offs.
Going back to the story of the Three Little Pigs: following the failure of each structure to withstand the Big Bad Wolf's huffing and puffing (and subsequent bacon snack), the next brother selected a stronger material in hopes of surviving. If you recall the end of the story, brother #3's stone structure not only succeeded in thwarting the wolf's attempts to blow it down, but also frustrated the wolf enough that he neglected to note the smoke coming from its chimney and dropped into a cauldron of boiling water, making a yummy soup for the apparently carnivorous pig. The main lesson learned in this fairy tale that applies to real life is that stone is a much better building material for resisting high winds than straw or sticks; the secondary lesson is that sometimes it takes one or more redesigns to achieve your goal.
ENGINEERING DESIGN OR TECHNOLOGY EDUCATION?
According to Williams (2010), the key difference between the design processes used in engineering and technology education "is that engineering design uses analysis and optimization for the mathematical prediction of design solutions" (p. 12). In other words, the engineering design process uses experimentation and mathematical modeling to verify a solution before building a prototype, while the design process in technology education uses experimentation and prototype modeling to develop the solution. Patterson, Campbell, Busch-Vishniac, and Guillaume (2011) propose that "special efforts have to be made in teaching to use exemplar applications that place engineering principles and ideas into the conditions surrounding the students on an everyday basis" (p. 213). In other words, students need context in what they are learning that establishes relevance of the content to be learned.
Too often, engineering content is very abstract, with concepts relevant to the subject matter but far removed from the context of everyday life. For instance, first-year undergraduate engineering students often learn about columns and beams, but not from the perspective of their relevance to the learner--that is, their importance in building homes, schools, churches, and other structures that fill their everyday lives. Rather, instructors make an assumption about prior knowledge that all learners have the same level of experience with abstract concepts within the instruction, which is often not the case. According to Patterson, et al. (2011), instruction that emphasizes familiar exemplar applications of such concepts using the "5Es (engage; explore; explain; elaborate; evaluate)" (p. 222) may be more effective in engaging less-experienced students than more traditional approaches to basic engineering education.
Often, though, many informal (and some formal) technology and engineering programs merely skim over the abstract concepts that are critical to the solid grounding that is needed for basic understanding, instead proceeding directly to learning activities exemplifying the concepts, often in design briefs, or shortened versions of instruction. Ates (2005) proposes that this is not always a bad thing, that students who have an opportunity to gain practical experience prior to conceptual learning may learn as effectively as traditional learners, especially in the cases where their prior experience is below average. However, he does not recommend that conceptual learning disappear from curriculum, only that it may be more effective to re-sequence it in the instruction. In this lesson plan, conceptual instruction occurs prior to the activity itself, but in a formal situation with enough time, students may benefit from a round of "play" prior to conceptual grounding.
LESSON PLAN CONTENT
In this lesson, students work in teams to learn and demonstrate various problem-solving techniques to solve a group structural problem consisting of designing and building a structure from construction paper and tape that is capable of supporting at least five pounds worth of weight in the form of textbooks. They apply science, technology, engineering, and math (STEM) concepts, including construction and communication skills, in completing the lesson's activities. Before beginning the team activities, Phelps grounds them in important basic physics concepts that include:
* Defining the concept of force as a vector having magnitude and direction.
* Differentiating between at-a-distance and contact forces.
* Demonstrating push (compression) versus pull (tensile) forces.
* Explaining the relevance of Newton's third law of motion, specifically, that for every action, there is an equal and opposite reaction.
* Defining stress as force divided by the area of the contact surface it rests upon.
Further, she instructs that structural members comprise vertical and horizontal components known as columns and beams. Beams typically rest atop two or more columns, which transfer the weight of the beam(s) and anything on top of them through the columns to the ground. In the case of single-story structures intended to be stationary, or in equilibrium, the downward gravitational force applied through the weight of the walls, beams, and roof is balanced by the equal and opposite reaction of the surfaces that the walls rest upon. Columns are often referred to as posts, which rest on footers typically formed from concrete to resist settling due to the lower density of soil versus stone or wood. The cross-sectional area of the post and footer determine how much stress the column and footer experience. Excessive stress is what causes failure, not necessarily excessive weight or force.
To cement that concept, Phelps has students evaluate three different cases as shown in Figure 1 to determine which undergoes the greatest stress. Not surprisingly, students often guess incorrectly that the waterbed is the culprit until they complete the stress calculations for each using the formula [sigma] = F/A. The correct answer is that the 125-pound woman wearing stiletto heels applies a stress of 125 pounds, divided by an area of (2 X [pi][(0.5).sup.2] ), or approximately 318 pounds per square inch (psi), compared to 0.9 psi for the refrigerator, and 0.7 psi for the waterbed. There were a number of surprised students in the classroom.
Columns typically fail due to a phenomenon known as buckling; their internal resistance to failure is overcome by the external forces acting upon them, such as compressive loads (e.g., snow on a roof) or shear loads (e.g., winds blowing nearly horizontally). Those external forces create an imbalance that results in one side of the column(s) experiencing compressive stress while the opposite side is under tension. Bridge footers, the supporting components that drop vertically through a body of water such as a river, are designed specifically to account for vertical loads due to the weight of the bridge itself along with the vehicles that cross it, and horizontal or shear loads due to moving wind, water, and debris contained within it. This lesson focuses on building structures, although it can also serve as an excellent introduction to a bridge-building lesson.
Following the conceptual grounding, which should take no more than 15 minutes, students break into teams and gather their needed materials: 25 sheets of standard 9" X 12" construction paper, 24" of either 1/2" wide masking or cellophane tape, a design brief defining the constraints, and a worksheet for modeling calculations. The design brief specifies that:
* The structure must be 12" high and self-supporting prior to placement of load.
* Each sheet of construction paper costs $2, each inch of tape costs $3.
* Tape may be cut into smaller pieces, but paper may not.
* The structure must support at least two textbooks to qualify (approximately 5#).
* The structure with the best effectiveness--as defined by the total cost of materials divided by its supported load--is the winner.
Depending on how much time is available and how many teams are participating, students spend 20 minutes or more designing and building a prototype to meet the design-brief requirements. Approximately two to three minutes should be allotted for each team's test to failure. The instructor should set up a firm surface area on the floor approximately 2' X 2' or more with 360[degrees] access for placement of the load (textbooks); see Figure 2. A chair or stepladder may be needed for well-built designs to enable the instructor to reach the top of the book tower. Assign one student to count as the instructor places the books on the structure. Videotaping provides a record of each test. The book that causes the structure to collapse does not count.
The instructor records the results on a chalk or whiteboard using the material cost calculation from each team's worksheet divided by the number of books their structure supported (effectiveness). The highest effectiveness wins. Following testing, students complete and submit worksheets for grading (if the lesson was part of a formal curriculum). A post-activity quiz in the form of a crossword puzzle provides another opportunity for formative assessment. Phelps gives students a rubric so that they can self-grade by the end of the lesson.
Given enough time, students may redesign their structure using a new set of materials. Although this lesson plan is intended for middle school students, additional enhancements could easily be made to make it more challenging for high school students-including 20% less materials, incorporation of different paper grades or tapes, or defining different physical constraints such as structure height.
This lesson plan accommodates technology, science, and math standards used in classrooms across the United States. Specifically, STL (ITEA/ITEEA, 2000/2002/2007) Standard 9 states that, "Students will develop an understanding of engineering design" (p. 99), with Benchmarks F, H, J, K, and L applicable, as listed:
* Benchmark F: Design involves a set of steps, which can be performed in different sequences and repeated as needed (p. 103).
* Benchmark H: Modeling, testing, evaluating, and modifying are used to transform ideas into practical solutions (p. 103).
* Benchmark J: Engineering is influenced by personal characteristics such as creativity, resourcefulness, and the ability to visualize and think abstractly (p. 104).
* Benchmark K: A prototype is a working model used to test a design concept by making actual observations and necessary adjustments (p. 105).
* Benchmark L: The process of engineering design takes into account a number of factors (p. 105).
Additionally, Standard 11 requires that "Students will develop the abilities to apply the design process" (p. 115), with Benchmarks J, K, L, N, O, P, and R applicable:
* Benchmark J: Make two-dimensional and three-dimensional representations of the design solution (p. 121).
* Benchmark K: Test and evaluate the design in relation to pre-established requirements, such as criteria and constraints, and refine as needed (p. 121).
* Benchmark L: Make a product or system and document the solution (p. 121).
* Benchmark N: Identify criteria and constraints and determine how these will affect the design process (p. 121).
* Benchmark O: Refine a design by using prototypes and modeling to ensure quality, efficiency, and productivity of the final product (p. 124).
* Benchmark P. Evaluate the design solution using conceptual, physical, and mathematical models at various intervals of the design process in order to check for proper design and to note areas where improvements are needed (p. 124).
* Benchmark R: Evaluate final solutions and communicate observations, processes, and results of the entire design process using verbal, graphic, quantitative, virtual, and written means, in addition to three-dimensional models (p. 124).
The Common Core State Standards for Mathematics (2010) also apply with respect to:
* Ratios and Proportional Relationships Standards 6 and 7, which address using ratio concepts, analysis, and reasoning to solve real-world problems (pp. 42 & 48).
* Numbering System Standards 6 and 7, which concern numeracy fluency and flexibility in problem solving (p. 48).
* Geometry Standards 6, 7, and 8, which involve solving real-world problems using area, surface area, and volume mathematics.
* Expressions and Equations Standard 6, which applies arithmetic to algebraic expressions.
* Functions Standard 8, involving modeling relationships between different quantities.
Finally, science and engineering standards from A Framework for K- 12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012) are addressed, specifically:
* Develop Scientific and Engineering Practices (a) ask questions and define problems, (b) develop and use models, (c) use mathematics and computational thinking, and (d) design solutions to problems.
* Develop Understanding of Core Ideas
** Physical Systems: (a) PS1 .A: Structure and Properties of Matter, (b) PS2.A: Forces and Motion, (c) PS2.B: Types of Interactions, (d) PS2.C: Stability and Instability in Physical Systems
** Engineering Design: (a) ETS1 .A: Define and Delimit an Engineering Problem, (b) ETSI.B: Develop Possible Solutions, and (c) ETSI.C: Optimize the Design Solution
Although informal outreach activities may not require either formative or summative assessments of student performance, there is some value in introducing students to the concepts of (a) self-assessment as a meta-cognitive tool, and (b) project-based performance reviews modeled after workforce evaluations. Identifying expected competencies and how proficiency is measured in a rubric enables students to develop and improve skills. In a formal classroom setting, Phelps assesses content knowledge using a crossword puzzle based on her conceptual grounding instruction (20%), effective teamwork and communication skills through observation and written reports (20%), and application skills through project performance (60%).
Phelps concurs with Ates (2005) that opportunities to use both mind and hands in a learning environment are very effective at transferring knowledge related to basic engineering concepts such as force and stress. Iteration of independent activities helps cement learning, especially when the student is interested in it (Patterson, Campbell, Busch-Vishniac, & Guillaume, 2011). This inexpensive formal or informal classroom activity can be completed in less than an hour (single design and build), or over several hours (one or more redesigns and/or enrichments). This video (www.youtube.com/watch?v=WsnPev2dTA, 2012) documents the current record known to Phelps: 41 textbooks, or not-quite 100 pounds, set by a group of high school students during a 2012 summer camp at a higher education institution in San Diego, CA. Judging from the hoots and cheers from the winning team's redesigned structure, students were very engaged with the activity; a follow-up assessment confirmed their engagement, as measured by an increased interest in engineering and technology fields.
Ates, S. (2005). The effectiveness of the learning-cycle method on teaching DC circuits to prospective female and male science teachers. Research in Science & Technological Education, 23(2), 213-227. doi: 10.1080/02635140500266518.
Committee on a Conceptual Framework for New K-12 Science Education Standards. (2012). A framework for K- 12 science education: Practices, crosscutting concepts, and core ideas. Retrieved from National Academies Press: http://research. cc.lehigh.edu/sites/gradresearch.cc.lehigh.edu/files/documents/VPRO/Workshops/NR C%20Framework%20for%20 K.12%20Science%20Education.pdf
International Technology Education Association (ITEA/ITEEA). (2000/2002/2007). Standards for technological literacy: Content for the study of technology. Retrieved from www. iteea.org/TAA/PDFs/xstnd.pdf
National Governors Association Center for Best Practices, Council of Chief State School Officers. (2010). The common core state standards: Mathematics. Retrieved from Common Core State Standards Initiative: www.corestandards.org/the-standards
Patterson, E. A., Campbell, P. B., Busch-Vishniac, I., & Guillaume, D. W. (2011). The effect of context on student engagement in engineering. European Journal of Engineering Education, 36(3), 211-224. doi: 10.1080/03043797.2011.575218.
Phelps, M. (2010). Forces and structural design. San Diego, CA.
Phelps, M. (2012, July 23). What goes up (video). San Diego, CA. Retrieved from www.youtube.com/watch?v=WsenPev2dTA
Phelps, M. (2013). What goes up, must come down: Integrated STEM lesson plan. San Diego, CA.
Thompson, S. J. (2013). The colorful storybook: Three little pigs. The Rhetorist. Retrieved from http://w8r.com/the-colorfulstory-book/three- little-pigs/
Williams, P. J. (2010). Technology education to engineering: A good move? Journal of Technology Studies, 36(2), 10-19.
Mary Phelps is an Occupational and Technical Studies doctoral student at Old Dominion University and expects to complete her dissertation on female engagement in nontraditional occupations in 2014. She can be reached at firstname.lastname@example.org.
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|Title Annotation:||RESOURCES IN TECHNOLOGY AND EGINEERING|
|Publication:||Technology and Engineering Teacher|
|Date:||Nov 1, 2013|
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