Hands-on Activity: Engineer a Coin Sorter

Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder


Students learn about the engineering design process and how it is used to engineer products for everyday use. Students individually brainstorm solutions for sorting coins and draw at least two design ideas. They work in small groups to combine ideas and build a coin sorter using common construction materials such as cardboard, tape, straws and fabric. Students test their coin sorters, make revisions and suggest ways to improve their designs. By designing, building, testing and improving coin sorters, students come to understand how the engineering design process is used to engineer products that benefit society.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Photo shows stacks of coins.
What's the best coin sorter?
Copyright © 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA. All rights reserved.

Engineering Connection

Engineers use the engineering design processes to create products we use daily. Everything from milk cartons to cars and toys were engineered using the steps of the engineering design process: design, build, test and improve.

Pre-Req Knowledge

Students should be able to accurately measure the diameters of the coins.

Learning Objectives

After this activity, students should be able to:

  • Explain that the engineering design process is iterative and explain how it improves the final product.
  • Explain that design is driven by function; form is secondary.
  • Suggest areas of improvement for the product (coin sorter) they create.

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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.

  • Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
  • Make two-dimensional and three-dimensional representations of the designed solution. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Design involves a set of steps, which can be performed in different sequences and repeated as needed. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Fluently add, subtract, multiply, and divide multidigit decimals using standard algorithms for each operation. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
Suggest an alignment not listed above

Materials List

Each group needs:

For the whole class to share:

  • a large jar of coins


(Hand out the What Do You Think? Pre-Assessment Worksheet and have students individually complete it before beginning the activity.)

A group of students ran a lemonade stand on their block all summer long. They called their company Cold & Tasty and charged 58 cents a glass. They accumulated buckets of change. Cold & Tasty wants to hire you as aspiring engineers to design a coin sorter to help them sort their buckets of change.

(Bring out a really large jar of coins.) Who wants to sort this jar of change?

(Divide the class into groups of two or three students each. Give each group a handful of change and ask them to sort and count it using a reliable method. Ask them to summarize their processes [how they did it] on blank paper or whiteboards.)

How would we go about designing a device to automatically sort these coins for us? (Use this as an introduction to the design process. Draw the engineering design process diagram on the board.)

As engineers, we first ask what the problem is and then imagine solutions. Next, we plan our design by drawing it out on paper and building it. Engineers always try to improve their designs so we will test our coin sorters and improve our designs to provide our customer, Cold & Tasty, with the best product possible.

(Bring out buckets of coins from Cold & Tasty.) Today, you're going to "put on your engineering hats," and design devices to sort the change for Cold & Tasty. Let's get started.


engineering design process: An iterative, step-by-step process used in engineering to design and improve technologies, objects and systems: 1) ask, 2) imagine, 3) plan, 4) create, and 5) improve.



Engineers use the engineering design process to invent and improve technologies, objects and systems. The engineering design process includes five basic and important steps:

  1. Ask: What is the problem? What have others done?
  2. Imagine: What is the best solution? Brainstorm ideas.
  3. Plan: Draw a diagram. List the materials you need.
  4. Create: Follow your plan and test it out.
  5. Improve: How can you improve your design? Go back to step 1.

Before the Activity

With the Students

1. Have students complete the Pre-Assessment Worksheet (as described in the Assessment section).

2. Divide the class into groups of two or three students each.

3. Conduct the Introduction/Motivation section. Bring out a really large jar of coins, saying "Who wants to sort this jar of change?" Engage the students in the simple sorting activity by asking each group to sort and count a handful of change. Ask students to summarize their processes (how they did it) on blank paper or whiteboards.

4. Introduce the design cycle. Draw the engineering design process diagram on the board. Explain that the engineering design process consists of five basic steps and is used by engineers around the world to invent and improve products, technologies, objects and systems that we use every day.

Diagram of five blue circles arranged in a circle with arrows pointing to the next circle with the following words in the circles: ask, imagine, plan, create, improve.
The steps of the engineering design process.
Copyright © 2009 Janet Yowell, ITL Program, College of Engineering, University of Colorado at Boulder.

5. Bring out buckets of coins from Cold & Tasty. Ask students to "put on their engineer hats" to design devices that can reliably and quickly sort the change.

6. The first step is to identify the problem. What is the problem we are trying to solve with the coin sorter? Tell students to spend about five minutes with their group asking each other what the problem is they are trying to solve. Have them imagine various solutions by talking about their ideas.

7. Hand out one math worksheet to each student. Have students prepare for their design by measuring the sizes of the various coins. Have them figure out which measurements they will need, make the measurements and record them on the worksheet. (The worksheet asks students to calculate the differences between measurements. Some students may require prompting that "difference" means subtraction.)

8. Hand out one design worksheet to each student. Explain that the worksheet contains two sides: the front is to be completed BEFORE building begins and the back is to be completed AFTER the coin-sorter has been built.

9. Have students complete the front of the worksheet by planning their coin sorters. Have them share ideas and draw their designs with labels indicating material choices. Allow enough time (~15-20 minutes) for students to complete detailed drawings.

10. While students are working, ask the following questions to the groups:

  • How will your coin-sorter work?
  • What properties of the coins can you use to sort them?
  • What materials will you use for each part of your design?

11. Be sure students have completed drawings before handing out materials.

12. Direct groups to begin creating their designs. Encourage students to test their designs during the building process.

13. Once students are done building their coin sorters, have them test and improve their designs.

14. Allow enough time for students to complete the worksheet (back side) and clean up.

15. Conclude with the post-activity assessments (see Assessment section) — individual design cycle reflections and class presentations by groups.

Photo shows a shoe box standing up vertically, with a funnel opening cut through the top and cardboard levels taped inside the box with variously-sized holes, and coins caught at every level.
Example student designed and built coin sorter.
Copyright © 2009 Jake Crosby, ITL Program, College of Engineering, University of Colorado at Boulder.


Troubleshooting Tips

Students new to the design process often get hung up on what "it" is going to look like (form) before they focus on how "it" works (functions). Address this if you see it happening. Use guiding questions to prompt students to focus on function—form follows function. Aesthetics is an important part of the design process, but no one wants a "pretty" product that does not perform.

Students also often forget about the iterative nature of design. Engineers go through many brainstorm-create-test-improve cycles before arriving at a final product.

The diameters of the different coins have minimal variation (at the mm level). But, if students use size to sort the coins, they must be precise; otherwise, they might run into the problem of larger coins plugging up the smaller holes. Help them trouble shoot this issue. Doing this is all part of the engineering process, so it can be a great teaching moment.


Pre-Activity Assessment

Accessing Prior Knowledge: Have students complete the What Do You Think? Pre-Assessment Worksheet. Use this assessment to understand students' ideas about how everyday products are designed by engineers. It is not meant to test whether or not students can memorize and recite the steps of the engineering design cycle.

  • Write a one sentence statement about what engineers do.
  • Write the steps you think engineers take when they design a new product.

Activity Embedded Assessment

Worksheet: Have students complete the front of the Engineer a Coin Sorter Design Worksheet before they begin building and the back of the worksheet after they have built their coin sorters, to document their activity. Review their answers to gauge their mastery of the subject.

Post-Activity Assessment

Design Cycle Reflection: What steps do engineers take to design new products? Write (or draw)—in your own words—the steps engineers take. For each step, write one sentence about why that step helps engineers create better products. The goal of this assessment is identify student thinking about the design process. Probe them to express their experiences and ideas about the process rather than parroting back the exact language of the design process steps. (Possible answers: Engineers first identify the problem or need they are solving and ask what has already been done to make sure they learn everything they can about the issues, and to not re-invent the wheel. Then they brainstorm (or imagine) as many options as possible to incorporate ideas from many points-of-view so as to increase creativity and innovation. Next, engineers pick the best solution and plan their designs. Planning leads to smart use of materials, time and funding, thereby increasing efficiency and helping to optimize performance under these constraints. After they plan, engineers iteratively create and improve. Testing makes sure it works and brings up problems and issues that weren't thought of before. Many iterations help to make the final product a better product.)

Class Presentation: Have students discuss the following topics within their groups. Assign one topic to each group and have students present their answers to the class.

  • Describe what questions your group asked at the beginning of this activity. (Possible answer: Expect students to explain the problems they are trying to solve and what other solutions already exist.)
  • What did your group imagine before you started planning? (Possible answer: Expect students to explain the different ideas they discussed before drawing their designs.)
  • Describe your group's plan. (Possible answer: Expect students to show their diagram and explain the materials they planned to use and why.)
  • How did you create your design? Did your plan change at all? (Possible answer: Expect groups to explain their building processes and what changed from their initial designs.)
  • Suggest changes that would improve the coin sorter. (Possible answer: Expect students to explain ways to redesign their coin sorters to improve their function.)

Activity Extensions

Encourage students to make a "business" using their coin sorters. Have students offer to sort a parent, sibling, neighbor or friend's loose change jar. Students could "charge" a 5% fee on however much money they count with their sorters. Ask students who do this activity extension to report their results to the class.

Activity Scaling

  • For lower grades, provide a lot of guidance during the planning and creating steps.
  • For upper grades, have students create a design that not only sorts coins, but also stacks them in paper coin tubes.


Coin Sorter. Activities from the Show, Engineering: Design It, ZOOM by kids, for kids, PBS Kids. Accessed February 3, 2010. (activity inspiration) http://pbskids.org/zoom/activities/sci/coinsorter.html

The Engineering Design Process. Engineering is Elementary, Boston Museum of Science, Boston, MA. Accessed February 17, 2010. http://www.mos.org/eie/engineering_design.php


Megan Schroeder; Stephanie Rivale


© 2009 by Regents of the University of Colorado.

Supporting Program

Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder


The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: November 28, 2018