Bridge Types

TeachEngineering Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Type Category
Instructional Materials
Experiment/Lab Activity , Instructor Guide/Manual , Lesson/Lesson Plan
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be "fully aligned," the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.




In this lesson, students will learn about three major types of bridges, identify tension and compression forces, and build models to discover how and where those forces act on each of the bridge types.  The lesson concludes with a choice of engineering scenarios: having students build a model bridge to fulfill a function, or consider several scenarios and decide on the best type of bridge for each. A Youtube video shows the scenarios, but while this may be useful for teacher preparation, the video should not be shown to students, so that they can figure things out for themselves.

Intended Audience

Educator and learner
Educational Level
  • Middle School
  • Grade 8
  • Grade 7
  • Grade 6
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

MS-ETS1-2 Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.

Clarification Statement: none

Assessment Boundary: none

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
This PE is addressed in the post-activity assessment called “Engineering Scenarios” in which students choose which bridge design or designs would work best for a particular situation. Connection to the entire PE can be strengthened by teaching students a process to use that would allow them to organize their findings from the models and from the information from the Introduction. (It is recommended that teachers use the Introduction after the models, to allow students to discover about the roles of the forces for themselves.)

MS-PS2-2 Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object.

Clarification Statement: Emphasis is on balanced (Newton’s First Law) and unbalanced forces in a system, qualitative comparisons of forces, mass and changes in motion (Newton’s Second Law), frame of reference, and specification of units.

Assessment Boundary: Assessment is limited to forces and changes in motion in one-dimension in an inertial reference frame and to change in one variable at a time. Assessment does not include the use of trigonometry.

This resource appears to be designed to build towards this performance expectation, though the resource developer has not explicitly stated so.

Comments about Including the Performance Expectation
This activity is designed to show how forces affect the stability, or lack thereof, for various bridge types. The models allow students to connect ideas about forces to the behavior of the bridge models. The activity will fit well into an instructional sequence after students have learned what forces are, and before asking them to design their own experiments.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Students use models to describe the forces that act on different parts of bridges. It is recommended that teachers use the “Engineering Scenarios” post-activity assessment, as this one has students use their findings to make predictions about appropriate bridge designs for different situations.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
The “Design your Own” and “Engineering Scenarios” post-activity assessments both involve students using their findings from the models in order to come up with solutions to problems. In “Design your Own”, students design a bridge. The teacher will want to specify criteria and constraints, focused on ideas from the models and from the information in the “Introduction” piece of the lesson. (Do the introduction after the models to allow students to discover ideas for themselves.) In “Engineering Scenarios”, students use their findings from the models, and information from the “Introduction”, to choose best-fit designs for given scenarios.

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
Students identify how combinations of compression and tension forces change the motion, or prevent the motion, of various types of bridges. It is recommended that the “Introduction” discussion of bridge types and the forces acting on them be saved until after the students build the models, so that students can discover for themselves how the forces affect each bridge type.

Crosscutting Concepts

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
Students use models to examine forces acting on various types of bridges, and to discover how making changes to the overall shapes or uses of materials can strengthen the bridges. E.g. What happens to the arch shape when buttresses are added? What happens to the suspension shape as the outer cables’ angle is increased?

Resource Quality

  • Alignment to the Dimensions of the NGSS: Students use core ideas about forces to explain the phenomena of changes in several model bridge types. They incorporate engineering ideas via a post-activity assessment where they choose best solutions for bridge engineering problems. The cross-cutting concept of structure and function is highlighted as students explore how making changes to a structure can alter its functional strength.

  • Instructional Supports: Students are familiar with bridges, but may not before have considered the different types, or about how decisions are made to build a bridge of one type or another. The worksheets that accompany the lesson are a bit closed-ended, and the after-activity assessments are a bit vague. The assessments could include a formal writing or oral presentation piece, and allow time for counterarguments and rebuttals. Suggestions are given for extensions, and the lesson includes picture support as well as a video that could be used to support ESL students or students with language processing difficulties.

  • Monitoring Student Progress: While the lesson offers several suggestions for assessments, scoring guidance is lacking. The Bridge Types and Forces worksheet, suggested as a formative assessment, will show student understanding of forces (a core idea) but not of structure and function, nor of the role of models in understanding phenomena.

  • Quality of Technological Interactivity: The lesson does not incorporate technological interactivity.