Critical Load

Nov 30 2012

Source: IEEE

Summary Information

Keywords:

civil engineering, design, motion, forces, buildings, structures, critical load

Topic:

Physical Science

Physics

Target Grade (Ages):

Grade 5 (Ages 10-11)

Grade 6 (Ages 11-12)

Grade 7 (Ages 12-13)

Grade 8 (Ages 13-14)

Estimated Time Required:

1-2 hours

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LESSON

Goals and Prerequisites

Goals:

Through this lesson, students will:

Learn about civil engineering and the testing of building structure.
Learn about efficiency ratings and critical load.
Learn about teamwork and the engineering problem solving.

Instructional Objective(s)

As a result of this activity, students should develop an understanding of:

efficiency ratings and critical load
structural design and testing
engineering problem solving
measurement and reporting
teamwork

Instructional Resources

Background:

The efficiency rating measures the weight that will cause a structure to fail divided by the weight of the structure itself. The most efficient structures are strong and lightweight - a difficult combination to achieve. For example, roofers in areas which experience heavy snows must factor in the weight of a massive snowstorm into designing the strength of the roof. The weight at which a building or structure fails is called the "critical load."

Materials:

One set of materials for each student team:
- twelve unused playing cards
- one roll of scotch tape
- 4 coins
Testing materials:
- Base of empty square based two quart cardboard
- juice/milk container
- Objects to build weight of base from 4 - 10
- pounds (coins, marbles, sand)
Student handout

Critical Load Student Worksheet

Procedure:

Provide each student team with materials and ask them to devise a structure that will hold the most weight. They are to plan out their structure, and build a prototype for testing. Allow 10 minutes for planning and execution.
Instructor places weights on each team's prototype increasing the weight until the structure fails. Students chart the maximum load each prototype successfully held (the amount just prior to failure)
Each student group presents their vision for their design, and explains why they think their design did well or failed. Ask students how would they adjust the design if they could do it again?

Extensions

Write an essay or a paragraph describing a recognizable building in your town. Include the history, interesting challenges to the building's engineering, and challenges that the engineers faced in design and construction.

Assessments and Rubrics

If you are interested in learning how to make your own rubric for this or other lessons, you may be interested in watching the How to Make a Rubric video below.

These reflective questions will help assess student understanding:

What was one thing you liked about your design? What is its main weakness?
What is one thing you would change about your design based on your experience?
Are there algebraic and physical principles that can be applied to this activity?
How would you modify the instructions to create a better experience for the participants?

External Resources

Credits

This lesson was originally created for TryEngineering by IEEE.

RESOURCES

Original Resources

Worksheets

Critical Load Student Worksheet

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