Hands-on Activity Model Heart Valves

Learning Objectives

After this activity, students should be able to:

• Follow the steps of the engineering design process to design and build a working prototype of a heart valve.
• Create an informational pamphlet that advertises a product, describing its function, benefits and effectiveness.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

Each group needs:

• computer with access to the internet, to research artificial heart valve ideas
• pitcher of colored water (add a few drops of red food coloring to the water)
• bucket (or access to a sink)
• a variety of items from the class source of supplies (listed below)
• a notebook or journal, for use as an engineering journal

For the class to share:

• a wide selection of various disposable materials, such as pieces of rubber (of different shapes and sizes), paper clips, ping pong balls, rubber bands, plastic sheets (of varying thicknesses), wire coat hangers, metal scraps, cardboard (miscellaneous pieces), cardboard rolls (from paper towel or toilet paper rolls), dental floss, and other miscellaneous household supplies
• general building materials, such as scissors, masking tape, duct tape, hot glue guns and glue sticks, rulers
• bottle of red food coloring

Note: The idea for the valve project is to provide an assortment of materials, but not direct groups towards any single solution. If desired, permit students to also bring in items from home to use. This way, students are designing their own valves and building them from their own plans. To level the playing field for the class, do not let them buy high-end supplies with their own money.

Worksheets and Attachments

Introduction/Motivation

After researching and learning about the heart anatomy and blood flow through the body, it's time to look at possible solutions to the challenge problem. In teams of three, your task is to design, build and test a prototype artificial heart valve to replace the defective one in your patient (your grandmother). If your first design does not perform as needed, redesign and rebuild your model. Once completed and tested, your team is tasked to create an informational pamphlet explaining your design.

Procedure

Background

Based on Lesson 2, Blood Pressure Basics, students should have a good understanding of heart valves by this point, and an idea as to the problems that valves can cause if they do not work correctly. In this activity, student should use the Challenge Question presented in Lesson 1, Heart to Heart, as the driving motivation for the design of their heart valves.

For reference, the following websites include activities in which students design heart valves:

Saving a Life: Heart Valve Replacement

and:

No Valve in Vain

Remind students that a heart valve must be able to open and close, as well as function as a one-way valve. This means their valves must be able to open to allow water (representing blood) to flow through the valve in one direction and be able to close to prevent water (blood) from passing through in the opposite direction.

Remind students to follow the steps of the engineering design process (as presented in Lesson 2, Blood Pressure Basics) and explain what they did in each step during the final presentations at the conclusion of the activity.

Before the Activity

• Divide the class into groups of three students each.
• Gather all activity materials and make copies of the grading rubric.

With the Students

Part I: Design/Build

1. Explain to students that their group engineering challenge is to design a prototype functioning artificial heart valve. Direct them to research current artificial heart valves to get ideas before they begin to brainstorm their own designs.
2. Do not pass out any of the materials to students, but show them what materials are available for building their valves. Give them a materials limit ("building within constraints" is a very important component of real-world engineering design) on the quantity of supplies they are permitted to use for their designs.
3. Inform students that after designing their heart valves, they must build a prototype using the available materials and any additional materials found at home.
4. To begin, direct students to draw in their engineering journals their group's brainstormed valve designs. Remind them to label all valve parts on the design drawing. Remind them to design the valve around the available supplies. (Note: Be aware that student devices are likely to be very crude because of the materials that they are using. This is okay, since the primary goal of the assignment is to ensure that students consider information about heart valves and blood pressure into account as they follow the steps of the engineering design process.)
5. While students are brainstorming, roam around the room and place three or four drops of red food coloring into students' pitchers of water. Remind them that this represents blood. They do not need to mix the drops into the water, as it will disperse adequately on its own.

Part II: Testing and Redesign

1. Explain to students that testing of the prototype design is best accomplished by observing it to make sure it moves in a way that allows fluid to flow through it.

   

2. Conduct testing in two phases by positioning the prototype heart valve over a bucket or sink.

• With the heart valve facing upward, have one student pour half the water in the pitcher on the model heart valve. In this direction, the valve should be open and should allow water to flow through.
• Then flip over the heart valve (or turn it upside down), and pour the remaining pitcher water on the heart valve. Now, the valve should close and prevent any water from passing through.

3. As they test, students should collect data in the form of observations and notes, and then continually redesign (iterate) until the valve functions as a true one-way valve.
4. Instruct student to retest their iterated designs. Remind them to make careful notes in their engineering journals to document design changes and results.

Part III: Product Marketing

1. After the model (re)design/build is complete, have teams design informational pamphlets or brochures that describe their prototype design, how it works, and why it is should be bought and used as a prosthetic for patients. Suggest that the marketing pieces include photographs and labeled diagrams showing parts and materials.
2. Have groups each present their artificial heart valve designs to the teacher and the rest of the class. Require presentations to include a water (blood) test and brochure explanation. Use the Heart Valve Model and Brochure Rubric to assess each valve. Notice whether it functions correctly by opening and closing (assuming blood would be pumping around it), as well as whether it and the brochure meet the other challenge requirements.

Assessment

Pre-Activity Assessment

Quick Review: Have each student list five facts they learned about blood pressure or heart valves in the previous lesson. In addition, have them list all the steps of the engineering design process with a brief sentence or two about each step.

Activity Embedded Assessment

Learn through Experimentation: Students should test their designs multiple times throughout the activity and record their observations in their engineering journals. Throughout the activity, ask students how their designs are coming along, how each test went, and what redesigning was necessary, based on test outcomes.

Post-Activity Assessment

Time to Share: Following the Heart Valve Model and Brochure Rubric, have each group present their artificial heart valve designs to the rest of the class to conclude the activity, describing the functionality and purpose of their designs. Require the presentations to include water (blood) demonstration tests, as well an explanation of their brochures. To make a connection to the Challenge Question that is central to this unit, have students apply their knowledge of the heart, heart diseases and defects, blood pressure and heart valves to persuasively explain how their heart valve design could be a solution to the Grand Challenge question.

Safety Issues

• Remind students to use caution when using scissors.
• Closely monitor the use of the hot glue guns, as it takes very little carelessness for a student to burn skin and clothing.
• Although it is not a safety hazard, watch that students do not flick colored water at each other, which could stain clothing.

Copyright

Contributors

Supporting Program

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.