(Lesson courtesy TeachEngineering.org, Integrated Teaching and Learning Program, the University of Colorado, Boulder, College of Engineering)

Grade Level: 10-12

Time: 3 hours (three class periods)

Summary

In this service-learning activity, student teams will learn the basic principles of fluid dynamics as well as how engineers improve society by designing a prototype system to pipe water from a storage tank to a simple hand-washing station called a Tippy Tap.  These inexpensive, homemade devices are used extensively in the developing world, but because they must be manually refilled with water, they are of limited use in high-traffic areas.

Learning Objectives

After this activity, students should be able to:

• Calculate pressure, velocity, and elevation in a simple piping system.
• Apply Bernoulli’s equation to simple pipe systems.
• Perform simple estimates of head loss due to pipe fittings.
• Explain how to conserve energy in piping systems and what contributes to energy losses.

Standards

International Technology Education Association Standards

• K. A prototype is a working model used to test a design concept by making actual observations and necessary adjustments. [Grades 9 -12]

Common Core State Standards for Mathematics

1. Explain each step in solving a simple equation as following from the equality of numbers asserted at the previous step, starting from the assumption that the original equation has a solution. Construct a viable argument to justify a solution method.  [Grades 9 – 12]

Prerequisite Knowledge

Students must have a basic knowledge of algebra, exponents, and how to use mathematical formulae. Prior exposure to the engineering design process is required. (Note: If students are unfamiliar with the design process, refer to http://www.teachengineering.org/engrdesignprocess.php or TeachEngineering’s Creative Engineering Design unit.)

Materials

Purchase the following items at any hardware or home improvement store (such as The Home Depot or Lowe’s). Total cost should run about $21.

Each group needs:

• Half-inch (inner diameter) PVC pipe, 5-ft (1.5m) length
• One-inch (inner diameter) PVC pipe, 5-ft (1.5 m) length
• 4 half-inch 90° PVC elbows
• 4 one-inch 90° PVC elbows
• 2 one-inch to half-inch PVC reducers
• miscellaneous PVC valves (butterfly, ball, globe, etc.)
• miscellaneous sizes of flexible (vinyl) tubing and barbed connectors
• duct tape
• Fluid Dynamics Basics Handout, one per person
• (optional) Brainstorming Guidelines

For the entire class to share:

• 1 Tippy Tap (or make one by following the attached Tippy Tap Construction instructions and these supplies: clean and empty one-gallon plastic milk jug, candle, matches, nail, pliers, plastic net, string or rope, metal support, knife, bar of soap, string, tin can lid)
• string or rope, 5 ft (1.5m) length
• five-gallon plastic bucket
• half-inch threaded PVC fitting
• drill and half-inch drill bit, to make a hole in the five-gallon bucket wall for the PVC fitting
• adhesive, to adhere the PVC fitting into the bucket wall
• water supply to fill a five-gallon bucket
• PVC pipe cutting tools, such as a saw or a 4-inch steel or PVC cutter.
• Towels or mop to clean up water spills (if conducting activity inside)

Introduction

Your local university’s Engineers Without Borders program has asked you to help on a sanitation project in Rwanda, Africa. The project aims to improve the health of children as young as 4, and as old as 20 who live in an orphanage in the community of  Mugonero.

According to the World Health Organization, about 38 percent of the world lacks access to improved sanitation,  which makes it unlikely that people wash their hands after bathroom use or before meals. Research has shown that washing hands with soap has been shown to reduce the risk of diarrheal disease by almost half. Thus, many people in underdeveloped countries suffer from diseases that could be prevented if they had a way to wash their hands regularly.

To this end, the Tippy Tap hand-washing station was developed and deployed in primarily rural communities in the developing world, such as Mugonero. The Tippy Tap (Figure 1 or the attached Tippy Tap Construction document) is a simple invention that enables hand washing without plumbing and with a fraction of the water used by a conventional/modern faucet with plumbing.

This device is made from a jug that releases a small amount of water when tipped. (See the Centers for Disease Control and Prevention construction and maintenance tip sheet.) Releasing the Tippy Tap causes it to swing back to its original position and stop the water flow. And, if a foot control is added, it becomes very hygienic because only the soap is touched.

Procedure

Fig. 2. Five-gallon bucket with a half-inch PVC fitting. Copyright © 2010 Benjamin S. Terry, ITL Program, College of Engineering, University of Colorado at Boulder

• Procure a Tippy Tap hand-washing station or build one using following the attached Tippy Top Construction instructions.
• Procure a five-gallon bucket to use as the water reservoir. Drill a hole in the side of the bucket at the bottom and use adhesive to attach a half-inch PVC fitting (see Figure 2).
• Gather materials and make copies of the Fluid Dynamics Basics Handout and (optional) Brainstorming Guidelines.
• Choose an appropriate location (outdoors is preferred) to test the piping systems created by the students.
• Set up the test area according to Figure 3.
• Suspend the Tippy Tap from a piece of playground equipment, a tree, etc. Note that the PVC fitting on the five-gallon bucket is 18 inches (46 cm) higher than the fill cap on the Tippy Tap and that the horizontal distance between the two is 60 inches (152 cm). Height above the ground is not critical, so choose a convenient height.
• Place an obstruction (as shown in Figure 3; can be anything, such as a large cardboard box) to ensure that students must use elbow style fittings or some other method to route the piping system in a non-direct path to the Tippy Tap.

With the Students – Day 1 (50 minutes)

With the Students – Day 2 (50 minutes)

With the Students – Day 3 (50 minutes)

Open-ended design projects can be difficult for students because no clear path to one solution exists. Keep students on task, working towards a feasible design, watching that they do not get stuck wasting too much time brainstorming or building unrealistic designs.

Assessments:

Post-Activity Assessment: Use the following suggested questions to lead a concluding discussion for this activity. Ask the students:

Homework As a homework assignment, have students answer the 11 questions in the Fluid Dynamics Basics Handout. Review their answers to gauge their understanding of the material.

It’s In Your Hands: see how easily two villagers make a Tippy Tap:

Additional Resources:

• Tippy Taps Construction (pdf)
• Brainstorming Guidelines (pdf)
• Brainstorming Guidelines (doc)
• Fluid Dynamics Basics Handout (pdf)
• Fluid Dynamics Basics Handout (doc)
• Fluid Dynamics Basics Handout Answers (pdf)
• Fluid Dynamics Basics Handout Answers (doc)

Other resources:

The Tippy Tap, a hand washing device with running water. [2:16] A Ugandan villager shows how to make a Tippy Tap in this YouTube video.

Tippy Tap technology and health facts from Tippytap.org

Contributors: Benjamin S. Terry, Kaisa Wallace-Moyer, Stephanie Rivale, Denise W. Carlson

© 2010 by Regents of the University of Colorado.

Filed under: Class Activities, Grades 9-12, Grades 9-12, Grades 9-12, Lesson Plans

Tags: Agricultural Engineering, Bernoulli, Class Activities, developing nation, energy conservation, Environmental Engineering, fluid dynamics, Grades 9-12, Lesson Plan, pipe systems, pipes, pressure, sanitation, service learning, velocity, Water